Electrophysiology catheter for mapping and/or ablation

ABSTRACT

The present invention encompasses apparatus and methods for mapping electrical activity within the heart. The present invention also encompasses methods and apparatus for creating lesions in the heart tissue (ablating) to create a region of necrotic tissue which serves to disable the propagation of errant electrical impulses caused by an arrhythmia.

CROSS REFERENCE TO RELATED APPLICATIONS

This divisional application claims the benefit under 35 U.S.C. §120 ofU.S. application Ser. No. 10/475,942, which issued as U.S. Pat. No.7,300,438, entitled “Electrophysiology Catheter For Mapping and/orAblation,” filed on May 10, 2004, which claims the benefit under 35U.S.C. §371 of International Application Serial No. PCT/US2002/10101,entitled “Electrophysiology Catheter For Mapping and/or Ablation,” filedMar. 29, 2002, which claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Application Ser. No. 60/287,057, entitled “Handles forMedical Devices,” filed Apr. 27, 2001, and U.S. provisional applicationSer. No. 60/345,119, entitled “Handle Thumb Wheel Mechanism WhichMaintains Holding Forces When Sterilized,” filed Oct. 19, 2001, all ofwhich are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to electrophysiology catheters, and moreparticularly to electrophysiology catheters for performing endocardialmapping and/or ablation procedures.

2. Discussion of the Related Art

The human heart is a very complex organ, which relies on both musclecontraction and electrical impulses to function properly. The electricalimpulses travel through the heart walls, first through the atria andthen the ventricles, causing the corresponding muscle tissue in theatria and ventricles to contract. Thus, the atria contract first,followed by the ventricles. This order is essential for properfunctioning of the heart.

In some individuals, the electrical impulses of the heart develop anirregular propagation, disrupting the heart's normal pumping action. Theabnormal heartbeat rhythm is termed a “cardiac arrhythmia.” Arrhythmiasmay occur when a site other than the sinoatrial node of the heart isinitiating rhythms (i.e., a focal arrhythmia), or when electricalsignals of the heart circulate repetitively in a closed circuit (i.e., areentrant arrhythmia).

Techniques have been developed which are used to locate cardiac regionsresponsible for the cardiac arrhythmia, and also to disable theshort-circuit function of these areas. According to these techniques,electrical energy is applied to a portion of the heart tissue to ablatethat tissue and produce scars which interrupt the reentrant conductionpathways or terminate the focal initiation. The regions to be ablatedare usually first determined by endocardial mapping techniques. Mappingtypically involves percutaneously introducing a catheter having one ormore electrodes into the patient, passing the catheter through a bloodvessel and into an endocardial site, and deliberately inducing anarrhythmia so that a continuous, simultaneous recording can be made witha multichannel recorder at each of several different endocardialpositions. When an arrythormogenic focus or inappropriate circuit islocated, as indicated in the electrocardiogram recording, it is markedby various imaging or localization means so that cardiac arrhythmiasemanating from that region can be blocked by ablating tissue. Anablation catheter with one or more electrodes can then transmitelectrical energy to the tissue adjacent the electrode to create alesion in the tissue. One or more suitably positioned lesions willtypically create a region of necrotic tissue which serves to disable thepropagation of the errant impulse caused by the arrythromogenic focus.Ablation is carried out by applying energy to the catheter electrodes.The ablation energy can be, for example, RF, DC, ultrasound, microwave,or laser radiation.

Atrial fibrillation together with atrial flutter are the most commonsustained arrhythmias found in clinical practice.

Current understanding is that atrial fibrillation is frequentlyinitiated by a focal trigger from the orifice of or within one of thepulmonary veins. Though mapping and ablation of these triggers appearsto be curative in patients with paroxysmal atrial fibrillation, thereare a number of limitations to ablating focal triggers via mapping andablating the earliest site of activation with a “point” radiofrequencylesion. One way to circumvent these limitations is to determineprecisely the point of earliest activation. Once the point of earliestactivation is identified, a lesion can be generated to electricallyisolate the trigger with a lesion; firing from within those veins wouldthen be eliminated or unable to reach the body of the atrium, and thuscould not trigger atrial fibrillation.

Another method to treat focal arrhythmias is to create a continuous,annular lesion around the ostia (i.e., the openings) of either the veinsor the arteries leading to or from the atria thus “corralling” thesignals emanating from any points distal to the annular lesion.Conventional techniques include applying multiple point sources aroundthe ostia in an effort to create such a continuous lesion. Such atechnique is relatively involved, and requires significant skill andattention from the clinician performing the procedures.

Another source of arrhythmias may be from reentrant circuits in themyocardium itself. Such circuits may not necessarily be associated withvessel ostia, but may be interrupted by means of ablating tissue eitherwithin the circuit or circumscribing the region of the circuit. Itshould be noted that a complete ‘fence’ around a circuit or tissueregion is not always required in order to block the propagation of thearrhythmia; in many cases simply increasing the propagation path lengthfor a signal may be sufficient. Conventional means for establishing suchlesion ‘fences’ include a multiplicity of point-by-point lesions,dragging a single electrode across tissue while delivering energy, orcreating an enormous lesion intended to inactivate a substantive volumeof myocardial tissue.

SUMMARY OF THE INVENTION

The present invention encompasses apparatus and methods for mappingelectrical activity within the heart. The present invention alsoencompasses methods and apparatus for creating lesions in the hearttissue (ablating) to create a region of necrotic tissue which serves todisable the propagation of errant electrical impulses caused by anarrhythmia.

According to one aspect of the present invention, an electrophysiologycatheter is provided. In one embodiment, the catheter comprises ahandle, a flexible shaft, a tip assembly, and a cable. The handle has adistal end and a proximal end and includes an actuator. The flexibleshaft has a proximal end and a distal end and a longitudinal axis thatextends along a length of the shaft, the proximal end of the shaft beingattached to the distal end of the handle. The tip assembly has aproximal end and a distal end, the proximal end of the tip assemblybeing attached to the distal end of the shaft. The distal end of the tipassembly is biased in an arcuately curved shape having a radius ofcurvature. The cable is attached to the actuator and the distal end ofthe tip assembly and extends through the shaft. The cable is adapted tochange the radius of curvature of the distal end of the tip assembly inresponse to movement of the actuator.

According to another embodiment of the present invention, anelectrophysiology catheter is provided that comprises a handle, aflexible shaft, a tip assembly, and a cable. The handle has a distal endand a proximal end and includes an actuator. The flexible shaft has aproximal end and a distal end and a longitudinal axis that extends alonga length of the shaft, the proximal end of the shaft being attached tothe distal end of the handle. The tip assembly has a proximal end and adistal end, the proximal end of the tip assembly being attached to thedistal end of the shaft. The proximal end of the tip assembly includes afixed bend of approximately ninety degrees relative to the longitudinalaxis of the shaft, and the distal end of the tip assembly includes anarcuate curve having a diameter, the arcuate curve being oriented in aplane that is approximately perpendicular to the longitudinal axis ofthe shaft. The cable is attached to the actuator and the distal end ofthe tip assembly and extends through the shaft. The cable is adapted tochange the diameter of the arcuate curve in response to movement of theactuator.

According to another embodiment of the present invention, anelectrophysiology catheter is provided that comprises a handle, aflexible shaft, a tip assembly, and first and second cables. The handlehas a distal end and a proximal end and includes a first actuator and asecond actuator. The flexible shaft has a proximal end and a distal endand a longitudinal axis that extends along a length of the shaft, theproximal end of the shaft being attached to the distal end of thehandle. The tip assembly has a proximal end and a distal end, theproximal end of the tip assembly being attached to the distal end of theshaft and the distal end of the tip assembly being biased in anarcuately curved shape and having a radius of curvature. The first cableis attached to the first actuator and the proximal end of the tipassembly and extends through the shaft. The first cable is adapted tobend the distal end of the tip assembly so that the distal end of thetip assembly is approximately perpendicular to the longitudinal axis ofthe shaft in response to movement of the first actuator. The secondcable is attached to the second actuator and the distal end of the tipassembly and extends through the shaft. The second cable is adapted tochange the radius of curvature of the distal end of the tip assembly ina plane that is approximately perpendicular to the longitudinal axis ofthe shaft in response to movement of the second actuator.

According to another aspect of the present invention, a handle isprovided for use with a catheter. In one embodiment the catheter has anelongated shaft and a tip assembly attached to a distal end of theelongated shaft. The shaft has a longitudinal axis that extends along alength of the shaft, and the tip assembly includes at least one cablefor changing at least one of a shape of the tip assembly and anorientation of the tip assembly relative to the longitudinal axis of theshaft. The handle comprises a housing and an actuator that is disposedon the housing. The actuator is attached to the at least one cable andmovable between a first position defining one of a first shape of thetip assembly and a first orientation of the tip assembly relative to thelongitudinal axis of the shaft and a second position defining one of asecond shape of the tip assembly and a second orientation of the tipassembly relative to the longitudinal axis of the shaft. The handlefurther comprises frictional means for imparting a first amount offriction on the at least one cable in the first position and forimparting a second amount of friction on the at least one cable when theactuator is moved away from the first position, the second amount offriction being greater than the first amount of friction.

According to another embodiment of the present invention, a handle foruse with a catheter having a proximal end and a distal end is provided.The catheter includes at least one cable for moving a portion of thedistal end of the catheter between a first position and a secondposition relative to the proximal end of the catheter. The handlecomprises a housing, an actuator disposed on the housing, the actuatorbeing attached to the at least one cable and movable between a thirdposition and a fourth position. The third position of the actuatorcorresponds to the first position of the portion of the distal end ofthe catheter relative to the proximal end of the catheter, and thefourth position corresponds to the second position of the portion of thedistal end of the catheter. The handle further includes frictional meansfor imparting a first amount of friction on the actuator when theactuator is in the third position and for imparting a second amount offriction on the actuator when the actuator is moved away from the thirdposition, the second amount of friction being greater than the firstamount of friction.

According to another aspect of the present invention, a handle for usewith a catheter having an elongated shaft and a tip assembly attached toa distal end of the elongated shaft is provided. The shaft has alongitudinal axis that extends along a length of the shaft, and the tipassembly includes at least one cable for changing a radius of curvatureof a distal end of the tip assembly. The handle comprises a housing, anactuator disposed on the housing, the actuator being attached to the atleast one cable and movable between a first position defining a firstradius of curvature of the distal end of the tip assembly and a secondposition defining a second radius of curvature of the distal end of thetip assembly, and graphical indicia indicative of the radius ofcurvature of the distal end of the tip assembly when the actuator is inat least one of the first position and the second position.

According to a further aspect of the present invention, a handle for usewith a catheter having an elongated shaft and a tip assembly attached toa distal end of the elongated shaft is provided. The shaft has alongitudinal axis that extends along a length of the shaft, and the tipassembly includes at least one cable for changing a radius of curvatureof a distal end of the tip assembly. The handle comprises a housing, anactuator disposed on the housing, the actuator being attached to the atleast one cable and movable between a first position defining a firstradius of curvature of the distal end of the tip assembly and a secondposition defining a second radius of curvature of the distal end of thetip assembly, and a plurality of protrusions, disposed on at least oneof the housing and the actuator, to provide tactile feedback to a userwhen the actuator is moved from the first position.

According to another aspect of the present invention, a method ofshaping a distal end of a catheter is provided. The method comprisesacts of placing the distal end of the catheter in a jig, maintaining thedistal end of the catheter and the jig at a predetermined temperaturefor a predetermined time, and removing the distal end of the catheterfrom the jig. The jig includes a passageway to receive the distal end ofthe catheter and hold the distal end of the catheter in a fixedposition. The passageway defines three contiguous regions including afirst straight region formed in a first plane, a second curved region inwhich the passageway bends within the first plane approximatelyperpendicularly to the first straight region, and a third curved regionin which the passageway curves arcuately in a second plane that isperpendicular to the first plane.

According to another aspect of the present invention, a jig for shapinga distal end of a catheter is provided. The jig comprises a mandrelhaving a passageway to receive the distal end of the catheter, and aretainer removably attached to the mandrel to hold the distal end of thecatheter within the passageway. The passageway defines three contiguousregions including a first straight region formed in a first plane, asecond curved region in which the passageway bends within the firstplane approximately perpendicularly to the first straight region, and athird curved region in which the passageway curves arcuately in a secondplane that is perpendicular to the first plane.

According to another aspect of the present invention, a method of usinga catheter is provided. The catheter includes a handle, a flexible shafthaving a longitudinal axis, and a tip assembly, the shaft beingconnected between the handle and the tip assembly. A distal end of thetip assembly includes an arcuate curve having a diameter. The methodcomprises acts of placing the tip assembly inside a heart of a patient,and remotely, from outside the patient, adjusting the diameter of thearcuate curve.

According to another embodiment, a method of using a catheter isprovided. The catheter includes a handle, a flexible shaft having alongitudinal axis, and a tip assembly. The shaft is connected betweenthe handle and the tip assembly. A proximal end of the tip assemblyincludes a fixed bend of approximately ninety degrees relative to thelongitudinal axis of the shaft, and the distal end of the tip assemblyincludes an arcuate curve having a diameter, the arcuate curve beingoriented in a plane that is approximately perpendicular to thelongitudinal axis of the shaft. The method comprises acts of placing thedistal end of the tip assembly inside a heart of a patient so that thearcuate curve of the distal end of the tip assembly contacts an innersurface of a heart vessel, and remotely, from outside the patient,applying a radially outward pressure with the distal end of the tipassembly against the inner surface of the heart vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative, non-limiting embodiments of the present invention aredescribed by way of example with reference to the accompanying drawings,in which:

FIG. 1 illustrates a schematic view of a mapping and/or ablationcatheter system in accordance with the present invention;

FIG. 2 is an end elevational view of a distal end tip assembly, takenalong line 2-2 in FIG. 1, that may be used with the catheter system ofFIG. 1 according to one embodiment of the present invention;

FIG. 3 is a perspective view of the distal end tip assembly of FIG. 2;

FIG. 4 is an alternative perspective view of the distal end tip assemblyof FIG. 2 illustrating the manner in which the radius of curvature ofthe distal end may be changed;

FIG. 5 illustrates a first jig that may be used to impart a fixed shapeto the distal end tip assembly according to one embodiment of thepresent invention;

FIG. 6 illustrates a side elevational view of the jig of FIG. 5;

FIG. 7 is a cross sectional side view of a second jig that may be usedto impart a fixed shape to the distal end tip assembly according toanother embodiment of the present invention;

FIG. 8 is an exploded perspective view of the jig of FIG. 7;

FIG. 9 is a cross sectional side view of a third jig that may be used toimpart a fixed shape to the distal end of the tip assembly according toanother embodiment of the present invention;

FIG. 10 is an exploded perspective view of the jig of FIG. 9;

FIG. 11 is an enlarged end elevational view of the distal end tipassembly of FIG. 2;

FIG. 12 is a schematic view of the distal end tip assembly of FIG. 11 ina tightly coiled position;

FIG. 13 is a schematic view of the distal end tip assembly of FIG. 11 ina loosely coiled position;

FIG. 14 is a side elevational view of the distal end of a finishedcatheter prior to shaping with any one of the jigs of FIGS. 5-10;

FIG. 15 is a cross sectional view of the distal end of the catheter ofFIG. 14 taken along line 15-15 in FIG. 14;

FIG. 15A is a fragmentary cross sectional view of the distal end of thecatheter of FIG. 15 showing an alternative raised profile electrode;

FIG. 16 is a cross sectional view of the distal end of the catheter ofFIG. 15 taken along line 16-16 in FIG. 15;

FIG. 17 is a cross sectional view of the distal end of the catheter ofFIG. 15 taken along line 17-17 in FIG. 15;

FIG. 18 is a perspective view of a distal end tip assembly according toanother embodiment of the present invention that may be used with thecatheter system of FIG. 1, and which includes a sliding electrode;

FIG. 19 is a cross sectional side view of the distal end tip assembly ofFIG. 18 taken along line 19-19 in FIG. 18;

FIG. 20 is a cross sectional end view of the distal end of tip assemblyof FIG. 19 taken along line 20-20 in FIG. 19;

FIG. 21 is a perspective view of a distal end tip assembly according toanother embodiment of the present invention that may be used with thecatheter system of FIG. 1;

FIG. 21A is a cross sectional view of the distal end tip assembly ofFIG. 21 taken along line 21A-21A in FIG. 21;

FIG. 22 is an exploded view of a handle, taken along line 22-22 in FIG.1, that may be used with the catheter system of FIG. 1 according toanother embodiment of the present invention;

FIG. 23 is a schematic cross sectional view of a slide actuator for thehandle of FIG. 22 in a neutral or unloaded state;

FIG. 24 is a schematic cross sectional view of a slide actuator for thehandle of FIG. 22 in a deployed or loaded state;

FIG. 25 is a cross sectional end view of the slide actuator of FIG. 23taken along line 25-25 in FIG. 23;

FIG. 26 is an exploded perspective view of the left section of thehandle of FIG. 22;

FIG. 27 is a schematic cross sectional view of a thumbwheel actuator forthe handle of FIG. 22 in a neutral or unloaded state;

FIG. 28 is a schematic cross sectional view of the thumbwheel actuatorfor the handle of FIG. 22 in a deployed or loaded state;

FIG. 29A is an elevational view of another handle that may be used withthe catheter system of FIG. 1 according to another embodiment of theinvention that includes a third actuator;

FIG. 29B is a schematic view of another handle according to anotherembodiment of the invention that includes a plunger-type third actuator;

FIG. 30 is a side elevational view of a handle that may be used with thecatheter system of FIG. 1 and which includes features that providetactile feedback to a user when using one of the actuators;

FIG. 31 is a schematic cross sectional view of one implementation forproviding tactile feedback to a user that is adapted for use with theslide actuator of FIG. 30;

FIG. 32 is a schematic cross sectional view of another implementationfor providing tactile feedback to a user that is also adapted for usewith the slide actuator of FIG. 30;

FIG. 33 is a side elevational view of an handle that includes graphicalindicia indicative of a radius of curvature of the distal end tipassembly according to another embodiment of the present invention;

FIG. 34 is a side elevational view of a distal end tip assemblyaccording to another embodiment of the present invention that includes alocalization sensor and a temperature sensor;

FIG. 35 illustrates the insertion of a catheter of the present inventioninto a body of a patient;

FIG. 36 illustrates the insertion of the catheter of the presentinvention into a heart; and

FIG. 37 illustrates the insertion of the distal end of the catheter intothe ostium of a pulmonary vein in the heart.

DETAILED DESCRIPTION

In this description, various aspects and features of the presentinvention will be described. One skilled in the art will appreciate thatthe features may be selectively combined in a device depending on theparticular application. Furthermore, any of the various features may beincorporated in a catheter and associated method of use for mappingand/or ablation procedures.

Catheter Overview

Reference is now made to FIG. 1, which illustrates an overview of amapping and/or ablation catheter system for use in electrophysiologyprocedures, in accordance with the present invention. The systemincludes a catheter 100 having a flexible shaft 110, a control handle120, and a connector 130. When used in mapping applications, theconnector 130 is used to allow signal wires running from mappingelectrodes at a distal end of the catheter 100 to be connected to adevice for recording signals, such as a recording device 160. When usedin ablation applications, connector 130 is used to allow signal wiresrunning from ablation electrodes at the distal end of the catheter 100to be connected to a device for generating ablation energy, such asablation energy generator 170. As will be described further in detailbelow, the distal end of the catheter 100 may include separate mappingand/or ablation electrodes, or may alternatively include electrodes thatare adapted for both mapping and ablation.

A controller 150 is electrically connected to connector 130 via cable115. In one embodiment, controller 150 may be a QUADRAPULSE RFCONTROLLER™ device available from C. R. Bard, Inc., Murray Hill, N.J.Ablation energy generator 170 may be connected to controller 150 viacable 116. Recording device 160 may be connected to controller 150 viacable 117. When used in an ablation application, controller 150 is usedto control ablation energy, provided by ablation energy generator 170,to catheter 100. When used in a mapping application, controller 150 isused to process signals from catheter 100 and provide these signals torecording device 160. Although illustrated as separate devices,recording device 160, ablation energy generator 170, and controller 150may be incorporated into a single device. It should further beappreciated that although both ablation energy generator 170 andrecording device 160 are illustrated in FIG. 1, either or both of thesedevices may be incorporated in the catheter system in accordance withthe present invention.

The shaft 110 of the catheter 100 is, in one embodiment, approximatelysix French in diameter, although it should be appreciated that manydiameters are possible, and the diameter of shaft 110 may be smaller orlarger depending on the particular application and/or combination offeatures incorporated into the catheter 100. Attached to a distal end112 of the shaft 110 is a distal end tip assembly 140 having a proximalend 142 that is attached to the distal end 112 of the shaft 110, and adistal end 144 having one or more electrodes 146 (See FIG. 2). Thelength of the tip assembly 140 may be approximately 7 to 8 cm in length,although other lengths may be suitably employed, as the presentinvention is not limited to any particular length. Further, and as willbe subsequently described, the number and placement of electrodes alongthe distal end 144 of the tip assembly 140 may vary depending upon theapplication. For example, for mapping applications, a plurality of lowprofile electrodes may be preferred, whereas for ablations applicationsa lesser number of higher profile electrodes may be preferred.Embodiments of the present invention may include as few as oneelectrode, which may be movably attached to the distal end 144 of thetip assembly 140, or may alternatively include a plurality of fixedelectrodes, for example 20 or more, spaced apart along the distal end142 of the tip assembly 140. Further, the construction of the electrodeor electrodes 146 may vary, as known to those skilled in the art.

According to one aspect of the present invention, and as shown in detailin FIG. 3, the proximal end 142 of the tip assembly 140 includes anapproximately ninety degree bend 148 relative to a longitudinal axis (L)of the shaft 110, which may be active, or fixed, and the distal end 144of the tip assembly 140 includes an arcuate curve that is orientedorthogonally to the longitudinal axis of the shaft 110. As used inassociation with the approximately ninety degree bend 148, the term“active” is herein defined to mean that the portion of the proximal end142 of the tip assembly 140 where the bend 148 is formed is capable ofmovement, relative to the longitudinal axis (L) of the shaft 110 betweenapproximately zero degrees and approximately ninety degrees viamanipulation of a remotely controlled actuator (e.g., actuators 122, 124disposed on the handle 120). The term “fixed,” as used in associationwith the approximately ninety degree bend 148, is herein defined to meanthat the approximately ninety degree bend 148 is permanently formed inthe proximal end 142 of the tip assembly 140, such that theapproximately ninety degree bend retains its shape at body temperatures.

According to a further aspect of the present invention, the radius (oralternatively, the diameter) of curvature of the arcuately curved distalend 144 may be adjustable by operation of an actuator (e.g., actuators122, 124) disposed on the handle 120. The combination of the approximateninety degree bend followed by an arcuate curve that is adjustable indiameter permits the catheter 100 to be uniquely suited for mappingand/or ablation procedures in difficult endocardial sites, such as, forexample, within a blood vessel, such as a pulmonary vein, or an ostiumof a blood vessel, such as the ostium of a pulmonary vein. For example,in both mapping and ablation procedures, the approximately ninety degreebend permits pressure, applied to the handle 120, to be translated tothe distal end 144 of the tip assembly 142, to thereby urge the distalend 144 of the tip assembly 140 tight against the endocardial site. Theadjustible radius of curvature of the arcuate curve can be used to applyan outwardly radial pressure to further force the distal end 144 of thetip assembly 140 tight against the endocardial site, or to adjust toendocardial sites of different diameters (e.g. that of an adult or largeanimal, or a small child or small animal), or both. This ability to urgethe distal end 144 of the tip assembly tight against an endocardial siteis advantageous in mapping procedures to better localize the source ofthe cardiac arrhythmia, and may be used in ablation procedures to focusthe ablation energy on the selected endocardial site. Further, becausethe radius of curvature of the distal end 144 of the tip assembly can beadjusted to different diameters, the catheter may be used with either anadult (or large animal) or a child (or small animal), as “one size fitsall.” This ability to accommodate a range of sizes can reduce the numberof distinctly sized catheters that need to be stocked by themanufacturer or the care provider.

Disposed on the handle 120 are one or more actuators 122, 124 that maybe used for a variety of purposes. Each of the actuators 122, 124 ismechanically coupled to at least one cable that extends to the tipassembly 140 and which may be used to change the shape, orientation, orboth the shape and orientation of the tip assembly. In the embodimentdepicted in FIG. 1, the handle 120 includes two different actuators, athumbwheel actuator 122 and a slide actuator 124. In one embodiment, thethumbwheel actuator 122 may be used to change the orientation of the tipassembly 140 in two opposing directions, and the slide actuator 124 maybe used to enlarge and decrease the radius of curvature of the arcuatelycurved distal end 144 of the tip assembly 140. As will be described indetail further below, the operation of the actuators 122, 124 may bereversed, such that the thumbwheel actuator 122 is used to control theradius of curvature, and the slide actuator 124 is used to control theorientation of the tip assembly 140 relative to the shaft 110 (e.g., toprovide steering). Moreover, as described further in detail below, thepresent invention is not limited to two distinct control actuators, asembodiments of the present invention may include only a single actuatorthat controls only one degree of movement (for example, increasing theradius of curvature of the arcuately curved distal end 144), or mayinclude several actuators, each capable of controlling two degrees ofmovement.

The Tip Assembly

FIGS. 2-4 illustrate a distal end tip assembly according to oneembodiment of the present invention. According to this embodiment, theproximal end 142 of the tip assembly 140 includes an approximatelyninety degree bend 148 relative to the longitudinal axis of the shaft110, followed by an arcuately curved distal end 144. In the embodimentdepicted in FIGS. 2-4, the approximately ninety degree bend 148 isfixed, that is, permanently formed in the proximal end 142 of the tipassembly 140, such that the approximately ninety degree bend 148 retainsits shape at body temperatures. In other embodiments, the approximatelyninety degree bend 148 may be active, that is, movable betweenapproximately zero and approximately ninety degrees relative to thelongitudinal axis (L) of the shaft 110 via a pull or push cable attachedto one of the actuators 122, 124 on the handle 120, as described furtherbelow with respect to FIG. 21.

In each embodiment, the region of the tip assembly 140 that includes theapproximately ninety degree bend 148 is preferably biased in a curvedposition relative to the longitudinal axis (L) of the shaft 110,although the degree of bias may vary. Specifically, in embodimentsfeaturing a fixed bend, the bend 148 is permanently formed in theproximal end 142 of the tip assembly 140 at an angle of approximatelyninety degrees, such that while capable of being straightened forintroduction into a vessel, such as for example, through the use of asheath/dilator, the distal end 144 of the tip assembly 140 springs backin its unrestrained state to rest in a plane that is approximatelyperpendicular to the longitudinal axis (L) of the shaft 110. Inembodiments featuring an active bend, only a slight amount of bend, forexample, a few degrees, is permanently formed in the proximal end 142 ofthe tip assembly 140. This slight amount of bend in the proximal end 142of the tip assembly 140 is sufficient to ensure that the distal end 144of the tip assembly 140 bends in a predetermined direction relative tothe longitudinal axis (L) of the shaft 110, as described more fullybelow. However, in all embodiments, the distal end 144 of the tipassembly 140 is permanently biased in an arcuate shape to facilitateincreases and/or decreases in the radius of curvature of the distal end144 of the tip assembly 140 in a known and controlled manner.

Disposed on the arcuately curved distal end 144 of the tip assembly 140are a plurality of ring-shaped electrodes 146 spaced uniformly apartalong the distal end 144 and a distal end tip electrode 147. Althoughillustrated as being uniformly spaced apart on the distal end 144 of thetip assembly 140, the electrodes 146 may alternatively be grouped inpairs, with the distance between each electrode of a pair being closerthan the distance between electrodes of adjacent pairs. For example,each ring electrode may be approximately 1 mm in length, with pairs ofelectrodes being spaced approximately 2 mm apart on center, and withelectrodes of adjacent pairs being spaced apart by approximately 8 mm.Furthermore, although the electrodes 146 illustrated in FIG. 2 are shownas being low profile ring electrodes that conform to the surface of thedistal end 144 of the tip assembly 140, they may also be raised inprofile. Indeed, as described further in detail below, embodiments ofthe present invention may be used with any type of electrode that issuitable for use in endocardial or epicardial mapping and/or ablationprocedures, as the present invention is not limited to the number, theconstruction, or placement of electrodes on the distal end 144 of thetip assembly 140.

According to an embodiment of the present invention, the tip assembly140 may be made from an elastomeric or polymeric thermodynamicbio-compatible material, such as PEBAX, that is bonded onto the distalend 112 of the flexible shaft 110, which may also be made from anelastomeric or polymeric thermodynamic bio-compatible material. Examplesof materials that may be used to form the flexible shaft 110 and the tipassembly 140 are well known in the art, and are described, for example,in commonly assigned U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777,which are hereby incorporated by reference in their entirety.

According to one embodiment of the present invention the flexible shaft110 may be made from a material that is stiffer than the material usedto form the proximal end 142 of the tip assembly 140, and the tipassembly 140 may be formed from a variety of bio-compatible materialsthat have different degrees of stiffness. For example, in oneembodiment, the flexible shaft 110 is made from a material having ahardness of approximately 60 Shore D, the proximal end 142 of the tipassembly is made from a material having a hardness of approximately45-50 Shore D, and the arcuately curved distal end 144 is made from amaterial having a hardness of approximately 40 Shore D. The increasedstiffness of the shaft 110 permits pressure applied to the handle 120 tobe more directly translated to the tip assembly 140. Further, theintermediate stiffness of the proximal end 142 of the tip assembly 140permits movement (i.e., steering) of the tip assembly 140 (describedfurther below) while ensuring that pressure applied to the handle 120 istranslated via the shaft 110 to the distal end 144 of the tip assembly140 to urge the distal end 144 of the tip assembly 140 tight against anendocardial site. Such enhanced contact is advantageous in both mappingand ablation procedures. Further, the relative flexibility of thematerial from which the distal end 144 of the tip assembly 140 is formedpermits the diameter of the arcuately curved distal end 144 of the tipassembly 140 to be changed (increased, decreased, or both) viamanipulation of one of the actuators 122, 124 on the handle 120. Inanother embodiment, the flexible shaft 110 is made from a materialhaving the same degree of hardness as the proximal end 142 of the tipassembly, for example, 45050 Shore D, but the flexible shaft 110 has alarger diameter, and is thus stiffer than the proximal end 142.

To further enhance contact with the endocardial site, the proximal end142 of the tip assembly 140 may be stiffened, for example with an outerstiffening tube (not shown), just ahead (i.e., proximally) of theapproximately ninety degree bend 148. For example, where the tipassembly 140 includes a fixed bend of approximately ninety degrees, thematerial forming the approximately ninety degree bend 148 may besufficiently stiffer than that from which the distal end 144 is formed,to further enhance contact with an endocardial or epicardial site.

Although embodiments of the present invention are not limited to anyparticular length, in one embodiment of the present invention, thelength of the flexible shaft is approximately one meter, the length ofthe proximal end 140 of the tip assembly is approximately 4.5 cm, thelength of the distal end 144 of the tip assembly is approximately 6.5cm, and the length of the approximately ninety degree bend portion isapproximately 0.7 cm. It should of course be appreciated that lengths ofthe different portions of the catheter may be varied, dependent upon theendocardial or epicardial site of interest.

As shown in FIG. 3, the tip assembly 140 may be movable (i.e.,steerable) in one or more directions perpendicular to the longitudinalaxis of the shaft 110. For example, as illustrated in the embodiment ofFIG. 3, the tip assembly 140 is capable of movement in two oppositedirections (shown as the Z axis) relative to the longitudinal axis ofthe shaft via manipulation of one of the actuators 122, 124 on thehandle 120 (FIG. 1). In other embodiments, the tip assembly may be movedin only a single direction (e.g., in the positive Z direction), or in anumber of different directions (e.g., in the positive and negative Zdirections, and the positive and negative Y directions).

As also shown in FIG. 3, and according to one aspect of the presentinvention, the radius (or alternatively, the diameter) of curvature ofthe arcuately curved distal end 144 of the tip assembly 140 may bechanged from a first diameter D1 to a second diameter D2. Preferrably,the radius of curvature of the arcuately curved distal end 144 of thetip assembly 140 may be increased and decreased via manipulation of oneof the actuators 122, 124 disposed on the handle 120. This ability toboth increase and decrease the radius of curvature of the distal end 144of the tip assembly 140 permits a single tip assembly 140 to be used ina wide variety of applications and with a wide variety of patients (fromadults or large animals to children or small animals), as it can beadjusted to different diameters to suit the requirements of the patientand the particular medical procedure. It also permits a radially outwardforce, or alternatively, a radially inward force, to be applied to anendocardial or epicardial site.

According to one embodiment of the present invention, the diameter ofthe arcuately curved distal end of the tip assembly is approximately 20mm in a resting state (corresponding to a neutral position of theactuator 122, 124 that controls the radius of curvature of the distalend 144 of the tip assembly 140), but may be decreased to a diameter ofapproximately 5 mm and increased to a diameter of approximately 50 mmvia manipulation of one of the actuators 122, 124. According to thisembodiment, the diameter of approximately 20 mm corresponds to anapproximately closed circle shown in FIGS. 2 and 3. The diameter ofapproximately 50 mm corresponds approximately to a semicircle, shown inphantom in FIG. 3, and the diameter of approximately 5 mm corresponds tomore than one complete circle (i.e., a spiraling of the distal end) asshown in FIG. 4. Although the present invention is not limited to anyparticular diameter for the distal end 144 of the tip assembly 140,these dimensions permit the catheter 100 to be well suited for use inmapping and/or ablation procedures relating to blood vessels where focaltriggers may be present, such as a pulmonary vein. For example, adiameter of approximately 5 to 50 mm permits the tip assembly to be usedfor mapping and/or ablation procedures relating to the ostium of apulmonary vein where focal triggers for cardiac arrythmias mayfrequently be encountered. These dimensions also permit a single tipassembly 140 to be used in either large or small humans or animals, andfor a wide variety of different procedures. It should be appreciatedthat the above-described dimensions for the diameter of the arcuatelycurved distal end of the tip assembly correspond to a radius ofcurvature that is one half that of the indicated diameter (i.e., adiameter of 50 mm corresponds to a radius of curvature of 25 mm, etc.).

Although the radius of curvature of the distal end 144 of the tipassembly 140 described with respect to FIG. 3 is preferably capable ofbeing increased or decreased, the present invention is not so limited.For example, in certain embodiments, the radius of curvature may bechanged in only first direction (e.g., increased), while in otherembodiments, the radius of curvature may only be changed in a seconddirection (e.g., decreased). However, in each of the above describedembodiments, the distal end 144 of the tip assembly 140 is preferablypermanently biased into an arcuate shape in its resting state so thatthe increase and/or decrease in the radius of curvature is achieved in aknown and controlled manner.

Steering and Control of the Tip Assembly

FIG. 11 is an enlarged end elevational view of the distal end tipassembly 140 of FIG. 2. As shown in FIG. 11, in one embodiment of thepresent invention, the distal end 144 of the tip assembly 140 includes apair of cables 110 a, 1110 b that may be used to change the radius (oralternatively, the diameter) of curvature of the distal end 144 of thetip assembly from a first diameter to a second diameter. In theembodiment illustrated in FIG. 11, the tip assembly includes a core 1120that includes a plurality of lumens, including a central lumen 1125, andfour coaxial lumens 1128 a-d disposed about the central lumen 1125. Thecentral lumen 1125 is used to hold one or more electrically conductivewires (not shown in FIG. 11) that are attached to respective electrodes146, 147 disposed along the distal end 144 of the tip assembly 140. Thefour coaxial lumens 1128 a-d may be used to hold cables that control theorientation of the tip assembly 140 relative to the shaft 110, and thatcontrol the radius of curvature of the distal end 144 of the tipassembly 140. As illustrated in FIG. 11, two cables 110 a and 110 bextend along the length of the distal end 144 of the tip assembly 140,while the two other cables (not shown) terminate prior to the distal end144. In the embodiment depicted in FIG. 11, the ends of the two cables110 a and 1110 b are tied together and potted with an epoxy adjacent themost distal end of the tip assembly 140. In this embodiment, the cables1110 a and 110 b are used to control the radius of curvature of thedistal end 144 of the tip assembly 140.

Although the tip assembly is described as including a core 1120 thatincludes a plurality of lumens 1125 and 1128 a-d, it should beappreciated that the tip assembly may be constructed in other ways. Forexample, U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777 describealternative constructions for the distal end of a catheter, some ofwhich include a central lumen that holds both the electrode wires andthe pull cables.

This alternative construction of the distal end tip assembly may also beused with embodiments of the present invention, as the present inventionis not limited to any particular construction.

FIGS. 12 and 13 illustrate how the radius of curvature of the distal end144 of the tip assembly 140 may be changed via manipulation of thecables 1110 a, 1110 b that are attached to one or more of the actuators122, 124 on the handle 120 (FIG. 1). In the embodiment illustrated,cables 1110 a and 1110 d are pull cables that may be formed, forexample, from stainless steel wire or any other suitable material. Wherethe catheter 100 is to be used in an environment where large magneticfields may be present, for example, in an MRI chamber, each of thecables (and indeed, the electrodes 146, 147) may be made fromnon-ferromagnetic materials. For example, the electrodes may be madefrom electrically conductive non-ferromagnetic materials such asplatinum, silver, or gold, while the cables may be made from compositematerials, such as carbon fiber, or KEVLAR™, or a multiplicity ofultra-high molecular weight polyethelene filaments. It should beappreciated that the cables 1110 a and 1110 b may alternatively be usedas push cables, although the use of push cables generally requires amore rigid and oftentimes larger diameter cable than that required for apull cable, which is operative under tension, rather than compression.As an example, the diameter of the pull cables may be in the range of0.003 to 0.004 inches.

As shown in FIGS. 12 and 13, tension applied to cable 1110 b results ina decrease in the diameter of curvature of the distal end 144 of the tipassembly 140 (and a corresponding slack in the cable 1110 a), whiletension applied to cable 110 a results in an increase in the diameter ofcurvature of the distal end 144 of the tip assembly 140.

FIG. 14 is a side elevational view of the distal end of a finishedcatheter 100 prior to shaping with any one of the jigs described withrespect to FIGS. 5-10 below. According to one embodiment of the presentinvention, the tip assembly 140 may be formed from several differentsections that are bonded together and to the shaft 110. The formation ofthe tip assembly in sections permits greater control of the diameter andstiffness of various sections. As illustrated in FIG. 14, these sectionsmay include a proximal section 1420 that is bonded to the flexible shaft110, an intermediate section 1480 which may be shaped to bendapproximately ninety degrees relative to the shaft 110 and which isbonded to the proximal section 1420, and a distal section 1440 that isbonded to the intermediate section 1480 and which includes a pluralityof electrodes and a distal end tip or cap electrode 147.

FIG. 15 is a cross sectional view of the distal end tip assembly 140 ofFIG. 14 taken along line 15-15 in FIG. 14. According to one embodimentof the present invention, the tip assembly 140 comprises a tubularproximal section 1420 and a tubular distal section 1440 alignedcoaxially with the shaft 110. Between the proximal section 1420 and thedistal section 1440 is an intermediate section 1480 that may be shapedto bend approximately ninety degrees relative to the shaft 110. Asillustrated, in one embodiment, the proximal section 1420 may be ofapproximately the same outer diameter as the shaft 110, and the distalsection 144 and the intermediate section 1480 can also be ofapproximately the same outer diameter, but a slightly smaller diameterthan the proximal section 1420 and the shaft 110. In other embodiments,the various sections forming the tip assembly 140 may be of the sameouter diameter as the shaft 110.

In the illustrated embodiment, the distal section 1440 of the tipassembly 140 terminates in a distal end or cap electrode 147 which isalso coaxially aligned with the shaft 110 and sections 1420, 1440, and1480. A threaded collar 1520 is secured to the distal end of distalsection 1440 to retain the electrode cap 147. It should be appreciatedthat other embodiments need not include the threaded collar 1520 and thedistal end or cap electrode 147, and may for example, instead utilize anon-conductive cap.

Shaft 110 may include a single lumen 1525 which extends the length ofthe shaft 110 from the distal end of the handle 120. The single-lumen1525 may be used to house the pull cables 1128 a-d and the electrodewires 1510. Each pull cable and each electrode wire preferably includesa sheath.

The electrical portion of the tip assembly 140 may include a pluralityspaced ring-type electrodes 146 along with a distal end or cap electrode147. The electrodes provide signal information on heart potentials tothe remote recording device 160 (FIG. 1) used by theelectrophysiologist. The ring-type electrodes 146 and the cap electrode147 are electrically connected to respective signal wires 1510. Thesignal wires 1510 are routed through the length of the core 1120 througha central lumen 1125 in each of the proximal 1420, intermediate 1480,and distal 1440 sections, as illustrated in FIGS. 15, 16, and 17 andattached to a respective electrode 146, 147. The signal wires 1510 arepreferably electrically insulated from each other and therefore may allshare a single lumen as shown. The signal wires 1510 extend proximallythrough the handle 120 to the connector 130 which enables the electrodes146 and 147 to be easily coupled electrically to the recording device160. In the illustrated embodiment, the two pull cables 1110 a and 1110b that extend nearly the length of the tip assembly 140 are used tocontrol the radius of curvature of the distal section 1440. The othertwo pull cables 1110 c and 11110 d are used to control bending of thetip assembly 140 in a plane that is perpendicular to the longitudinalaxis (L) of the shaft 110 (See FIG. 14). As shown in FIGS. 15, 16, and17, the pull cables 1110 c and 1110 d terminate proximally of theintermediate section 1480. In one embodiment, each of the pull cables1110 c and 11110 d terminates in a ball 1530 which may be made from anysuitable material, and which is larger in diameter than the lumens 1128c and 1128 d in which the pull cables are housed. For example, each ofthe pull cables 1110 c and 1110 d may be passed through a hole in theball (not shown) and the end tied to prevent the cable from comingloose. Other methods of terminating the cables 1110 c and 1110 d aredescribed in the aforementioned patents, for example, by tying the endsof the cables 128 c and 1128 d together at a distal end of proximalsection 1420.

It should be appreciated that an additional pair of pull cables may alsobe provided to control bending of the tip assembly 140 in a plane thatis perpendicular to the longitudinal axis of the shaft 110 andperpendicular to the other plane of motion provided by pull cables 1110c and 1110 d. Thus, depending upon the number of pull cables and thenumber of actuators disposed on the handle 120, the radius of curvatureof the distal end of the tip assembly 140 may be increased or decreased,and the orientation of the tip assembly 140 may be changed in twodifferent directions in each of two orthogonal planes (e.g., a Y planeand a Z plane) that are perpendicular to the longitudinal axis of theshaft.

The proximal section 1420 includes a central lumen 1125 for passing allof the electrode wires 1510 to the intermediate 1480 and distal 1440sections, and for passing two of the pull cables 110 a and 110 b. Theproximal section 1440 also includes two proximal cable lumens 1128 c and1128 d which pass pull cables 1110 c and 1110 d from the lumen 1525 inthe shaft 110 through the length of the proximal section 1420. Proximalcable lumens 1128 c and 1128 d may contain respective stiffening wires1710 (FIG. 17) to reduce axial twisting of proximal section 1420. Theproximal section 1420 includes a reduced diameter proximal end so thatthe proximal section 144 may be mated to the distal end of the shaft,within the distal end of the shaft 110.

The intermediate section 1480 is thermally bonded to the distal end ofthe proximal section 1420 and the proximal end of the distal section1440. The intermediate section 1480 includes two reduced diameter endsso that it may snugly nest inside the proximal and distal sections. Theintermediate section 1480 includes two cable lumens 1128 a and 1128 band a central lumen 1125. Additional lumens may also be included, asdescribed further below. Pull cables 1110 a and 1110 b from the centralproximal section lumen 1125 are routed to the outwardly disposed cablelumens 1128 a and 1128 b, respectively, at a point just past the distalend of the central lumen 1125 of the proximal section 1420. A smalltransition space is provided between the lumens of the intermediate andproximal sections to permit the pull cables 1110 a, 1110 b to beradially displaced.

The distal section 1440 is thermally bonded to the distal end of theintermediate section 1480 and has approximately the same outer diameteras the intermediate section 1480. The distal end of the intermediatesection 1480 is recessed within the distal section 1440 to provide asmooth transition between the two sections. The distal section 1440 alsoincludes two cable lumens 1128 a and 1128 b and a central lumen 1125.The distal section 1440 may also include additional lumens (shown inFIG. 16), that may be used, for example, to house a control wire for asliding electrode, to house an irrigation line, to house a wire for alocalization sensor, etc. The ends of the pull cables 1110 a and 1110 bemanating from the outwardly disposed cable lumens 1128 a and 1128 b,respectively, may be tied together and/or potted with an epoxy. Theelectrode wires 1510 from the central lumen 1125 are fed through radialapertures in the core 1120 and soldered or welded (or bonded with aconductive epoxy) onto an undersurface of the ring electrodes 146, asillustrated in FIGS. 15A and 16. The wire for the distal end or capelectrode may be fed through the central lumen 1125 and soldered,welded, or epoxied onto the cap electrode 147.

In the embodiment illustrated in FIG. 15, each of the plurality of ringelectrodes 146 are recessed within the outer circumferential surface ofthe distal section to provide a low profile. However, for certainprocedures, such as ablation, it may be preferable to have the outersurface of one or more of the electrodes 1546 protrude above the outercircumferential surface of the distal section, such as illustrated inFIG. 15A, and illustrated in phantom in FIG. 16. It should beappreciated that a variety of different types of electrodes may be usedwith the tip assembly depicted in FIG. 15, as the present invention isnot limited to any particular type, or construction of electrode.

Various configurations can be used to locate and anchor the pull cableswithin the shaft and the proximal, intermediate and distal sections ofthe tip assembly. In general, it is preferable to conduct the pullcables as close as possible to the outer circumference of the sectioncontrolled by the cables in order to increase the bending moment. Forthis reason, the controlling cables for both the proximal and distalsections are directed to outer lumens, i.e., lumens 1128 c and 1128 dand lumens 1128 a, 1128 b. However, prior to reaching the section thatis controlled by the cables, the cables are preferably centrally routed,for example in central lumen 1125, so that manipulation of cablescontrolling movement of more distal sections of the catheter do notaffect the orientation of more proximal sections of the catheter. Theillustrated construction has been found to be an optimal arrangementfrom the points of view of manufacturing ease and function. Otherarrangements, however, can also be used. For example, the pull cablescan be conducted through the proximal, intermediate, and distal sectionsexclusively through outer lumens. Examples of other arrangements for thepull cables within the tip assembly 140 are described in theaforementioned U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777.

Active Bend

As noted above, the approximately ninety degree bend in the distal endtip assembly 140 may be either fixed (e.g., permanently formed with theuse of a jig, such as jigs 500, 700, and 900, described in detail withrespect to FIGS. 5-10 below), or active (e.g., movable betweenapproximately zero and approximately ninety degrees relative to thelongitudinal axis of the shaft 110 of the catheter 100) through the useof an actuator 122, 124 disposed on the handle 120. FIGS. 21 and 21Aillustrate an embodiment of the present invention that includes such an“active bend.”

As shown in FIG. 21, in one embodiment, the distal end tip assembly 140includes a proximal section 2120, an intermediate section 2180 that maybe actively bent via manipulation of a control cable (FIG. 21A) attachedto an actuator (e.g., actuator 122) on the control handle 120 to beapproximately perpendicular to the longitudinal axis of the shaft 110,and a distal section 2140 having a radius of curvature that can beadjusted via manipulation of a control cable attached to an actuator(e.g., actuator 124) on the handle 120. The distal section 2140 includesone or more electrodes 146, 147 disposed along a length of the distalsection 2140.

As shown in FIG. 21A, which is a cross section of the proximal section2120 of the tip assembly 140 taken along line 21A-21A in FIG. 21, thecables 1110 c and 1110 d that control bending of the intermediatesection 2180 may be formed from a single cable that is wrapped around areduced diameter end of the proximal section 2120 and that is recessedwithin the intermediate section 2128 in a manner similar to thatdescribed with respect to FIG. 12 in U.S. Pat. No. 5,383,852. Ingeneral, the cable will be wrapped about that portion of the tipassembly that is immediately prior to the point at which bending is tooccur. In this embodiment, tension applied to cable 1110 c results abending of the distal section 2140 of the tip assembly 140 in a downwarddirection (as seen in FIG. 21) to orient the arcuately curved distalsection 2140 in a plane that is perpendicular to the longitudinal axisof the shaft 110, and tension applied to cable 1110 d results in thebending of the distal section 2140 of the tip assembly 140 in an upwarddirection (as seen in FIG. 21) to return to its position along thelongitudinal axis of the shaft. Because the handle 120 may be rotatedone hundred and eighty degrees, the ability to bend the distal sectionin an opposite direction is unnecessary, but may be provided, ifdesired. It should be appreciated that in other embodiments, only asingle control wire may be used.

To accommodate such an active curve, the material from which theintermediate section 2180 is formed should be less stiff than thematerial from which the shaft 110 is formed so that bending occurs inthe intermediate section 2180. Preferably, the material from which thedistal section is formed is less stiff than that from which theintermediate section is formed to permit the radius of curvature of thedistal section 2140 to be changed without altering the orientation ofthe intermediate and proximal sections 2180 and 2120, respectively.

To facilitate bending in a known and controlled manner, the intermediatesection 2180 is preferably permanently biased to have a bend of a fewdegrees relative to the longitudinal axis (L) of the shaft 110. Becausethe intermediate section 2180 is permanently biased a few degrees awayfrom the longitudinal axis (L) of the shaft 110, tension applied tocable 1110 c, for example, results in bending of the intermediatesection 2180 in the plane of the bend toward a ninety degree angle withthe longitudinal axis (L) of the shaft 110. Tension applied to theopposing cable, for example 1110 d, results in bending of theintermediate section 2180 in the plane of the bend back toward thelongitudinal axis (L) of the shaft 110. Because the intermediate section2180 is biased a few degrees away from the longitudinal axis (L) of theshaft 110 in a particular direction, any bending of the intermediatesection 2180 occurs in the plane aligned in the same direction as thatbend in a known and controlled manner. Were the intermediate section2180 not biased in a particular direction, bending could occur in anydirection.

Electrode Configurations

As noted above, embodiments of the present invention are not limited toa particular construction, type, or number of electrodes disposed alongthe distal end of the tip assembly. For example, embodiments of thepresent invention may include a plurality of low-profile ring typeelectrodes 146 disposed along the distal end of the tip assembly 140,such as shown in FIG. 2, with or without a distal end or cap electrode147. Alternatively, a plurality of raised profile ring type electrodesmay be used, such as the electrode 1546 illustrated in FIG. 15A, with orwithout a distal end or cap electrode 147. Alternatively still, acombination of raised and low profile electrodes may be used.

Where multiple mapping electrodes are used, pairs of mapping electrodes146 (FIG. 2) may be used to determine a location of lowest conductivityon the septal wall, or a preferred location to puncture the septal wallduring a transeptal procedure. Each of the mapping electrodes 146 maydetect a voltage signal, which is transmitted to controller 150 viacable 115 (FIG. 1). Voltage may be measured instantaneously orcontinuously by each of the electrodes 146. Continuous voltagemeasurements generate an electrogram (a voltage signal that changes withtime) for each electrode. The voltage detected by each electrode may bedetermined with respect to a reference electrode, termed a unipolarvoltage measurement, or may be determined with respect to anotherelectrode of a pair, termed a bipolar voltage measurement. Thus, a pairof mapping electrodes may generate two unipolar electrograms, each withrespect to a reference electrode located elsewhere on the catheter 100,or a single bipolar electrogram representing the voltage between eachpair of electrodes. As unipolar and bipolar voltage measurement are wellunderstood by those skilled in the art, further discussion is omittedherein.

It should be appreciated that the electrodes may be constructed from avariety of materials, including non ferromagnetic materials such asgold, platinum, and silver, or they may be constructed from a conductiveepoxy. The electrodes may be individual electrodes, or may be continuouselectrodes, similar in construction to a coiled spring wrapped about thedistal end of the tip assembly. The electrodes may be fixed in positionalong the distal end of the tip assembly, or alternatively, may bemovable along a length of the distal end of the tip assembly. An exampleof such a movable electrode is now described with respect to FIG. 18.

As shown in FIG. 18, the distal end 144 of the tip assembly 140 mayinclude a movable electrode 1846 that is movable between a firstposition and a second position spaced apart along a length of the distalend 144 of the tip assembly 140. In the embodiment illustrated, themovable electrode 1846 slides along a length of the distal end 144 thanspans approximately 360 degrees, and when used for ablation, may be usedto form a circular lesion. The very distal end of the tip assembly mayinclude a cap electrode 1847, or alternatively, the cap may be made froma non-conductive material and may simply serve to terminate the verydistal end of the tip assembly. Where a cap electrode 1847 is used, aninsulating spacer may be placed proximally of the cap electrode toprevent the movable electrode 1846 from electrically contacting the capelectrode 1847.

As shown in FIG. 19, which is a cross sectional side view of the distalend of the tip assembly in FIG. 18 taken along line 19-19, the electrode1846 may be attached to a cylindrically-shaped plastic slider 1910 thatthat can slide back and forth along a length of the distal end 144 ofthe tip assembly. In the embodiment shown, the distal end of a metalpush/pull wire 1920 is welded to an outer surface of the electrode 1846,with the proximal end of the push/pull 1920 wire being attached to anactuator 122, 124 on the handle 120. The push/pull wire 1920 may bedisposed within the central lumen 1125 from the handle 120 to theintermediate section 1480 of the tip assembly 140 (FIG. 15), wherein itthen passes through one of the outer lumens 1110 c, 1110 d of the distalsection. The distal end of the push/pull wire 1920 emanates through aslit 1930 in the core 1120. It should be appreciated that in embodimentswhere it is desired that the push/pull wire 1920 not be electricallyconnected to the electrode, the push/pull wire 1920 may be attached tothe plastic slider 1910, rather than to the electrode 1846. It shouldalso be appreciated that the push/pull wire 1920 need not be made frommetal, as non-conducting materials may also be used, as known to thoseskilled in the art.

FIG. 20 is a cross sectional end view of distal end of the tip assemblyillustrated in FIG. 19, taken along line 20-20. FIG. 20 illustrates theslit 1930 in the core 1120 through which the push/pull wire 1920protrudes, with the remaining elements having already been described.Further details of the sliding electrode described with respect to FIGS.18-20 are provided in commonly assigned U.S. Pat. No. 6,245,066, whichis hereby incorporated by reference in its entirety.

The Handle

A handle assembly in accordance with one embodiment of the invention, isshown in FIGS. 22-33. The handle configuration shown in these drawingsuses rotational movement of the thumbwheel actuator 122 to selectivelycontrol the tension applied to the pull cables 1110 c and 1110 d whichcontrol the orientation of the tip assembly 140 relative to thelongitudinal axis of the shaft 110, and linear movement of the slideactuator 124 to selectively control the tension applied to pull cables1110 a and 1110 b that control the radius of curvature of the distal end144 of the tip assembly 140.

Referring to FIG. 22, the handle 120 comprises a housing having a leftsection 2200L and a right section 2200R. These two sections 2200L and2200R are somewhat semicircular in cross section and have flatconnecting surfaces which may be secured to each other along a commonplane to form a complete housing for the handle 120. The outer surfacesof the handle 120 are contoured to be comfortably held by the user.

A wheel cavity 2210 is formed within the right section 2200R of thehandle 120. The wheel cavity 2210 includes a planar rear surface 2211which is generally parallel to the flat connecting surface of the handle120. The thumb wheel actuator 122 is a generally circular disc having acentral bore 2216, an integrally formed pulley 2218, and upper and lowercable anchors 2220. Upper and lower cable guides 2221 serve to retainthe cables 1110 c and 1110 d within a guide slot or groove 2223 formedin a surface of the integrally formed pulley 2218. In the embodimentillustrated, the thumbwheel 122 rotates about a sleeve 2228 inserted inthe central bore 2216. The thumbwheel 122 is held in position by ashoulder nut 2224 that mates with a threaded insert 2229 in the planarrear surface 2211 of the right section 2200R of the handle 120. Toprovide friction that permits the thumbwheel to maintain its positioneven when tension is applied to one of the cables 1110 c, 1110 d, afriction disk 2226 is provided between the shoulder nut 2224 and thethumbwheel 122. Tightening of the shoulder nut 2224 increases the amountof friction applied to the thumbwheel 122.

A peripheral edge surface 2222 of the thumb wheel 122 protrudes from awheel access opening so that the thumb wheel 122 may be rotated by thethumb of the operator's hand which is used to grip the handle 120. Toensure a positive grip between the thumb wheel 122 and the user's thumb,the peripheral edge surface 2222 of the thumb wheel 122 is preferablyserrated, or otherwise roughened. Different serrations on oppositehalves of thumb wheel 122 enable the user to “feel” the position of thethumb wheel.

The left section 2200L supports part of the mechanism for selectivelytensioning each of the two pull cables 1110 a and 110 b that control theradius of curvature of the distal end 144 of the tip assembly 140. Toaccommodate the protruding portion of the thumb wheel 122, the lefthandle section 2200L includes a wheel access opening similar in shape tothe wheel access opening of the right handle section 2200R. It alsoincludes an elongated slot 2230 in its side surface.

A slider 2232 is provided with a neck portion 2242 which fits snuglywithin the slot 2230. The slider 2232 includes a forward cable anchor2235 and a rear cable anchor 2236 for anchoring the pull cables 1110 aand 1110 b. Pull cable 1110 b is directly attached to the forward cableanchor 2235 and becomes taught when the slider 2232 is moved toward thedistal end of the handle 120. Pull cable 1110 a is guided by a returnpulley 2238 prior to being attached to the rear cable anchor 2236 andbecomes taught when the slider 2232 is moved toward the proximal end ofthe handle 120. The return pulley 2238 is rotatably attached to a pulleyaxle 2239 which is supported in a bore (not shown) in the flat surfaceof the right handle section 2200R. The return pulley 2238 may include agroove (not shown) to guide pull cable 1110 a. In the illustratedembodiment, a cable guide 2205 is attached to the right handle section2200R to guide the cables 1110 a-1110 d and prevent their entanglementwith one another. As shown, cables 110 a and 1110 b are routed up andover the cable guide 2205, while cables 1110 c and 1110 d are routedthrough a gap 2206 in the cable guide 2205. Grooves may be formed in atop surface of the cable guide 2205 to keep cables 1110 a and 1110 b inposition, although they could alternatively be routed through holesformed in the cable guide 2205, or by other suitable means.

A slider grip 2252 is attached to the neck portion 2242 of the slider2232 and positioned externally of the handle 120. The slider grip 2252is preferably ergonomically shaped to be comfortably controlled by theuser. Together, the slider 2232 and the slider grip 2252 form the slideactuator 124 depicted in FIG. 1. Preload pads 2254 are positionedbetween the outer surface of the left handle section 2200L and theslider grip 2252 (shown in FIGS. 22 and 25). By tightening the screws2260 that attach the slider grip 2252 to the slider 2232, friction isapplied to the slider 2232 and thus, to the pull cables 1110 a, 1110 b.Preload pads 2237 may also be placed on a surface of the slider 2232 fora similar purpose.

A dust seal 2234 (FIGS. 22 and 26) having an elongated slit andpreferably made from latex is bonded along the slot 2230 within the lefthandle section 2200L. The neck portion 2242 of the slider 2232 protrudesthrough the slit of the dust seal 2234 so that the slit only separatesadjacent to the neck portion 2242. Otherwise, the slit remains “closed”and functions as an effective barrier preventing dust, hair and othercontaminants from entering the handle 120. Further details of the handle122 are described in U.S. Pat. Nos. 5,383,852, 5,462,527, and 5,611,777.

According to a further aspect of the present invention, each of thethumbwheel actuator and the slide actuator may include means forimparting a first amount of friction on at least one pull cable to whichthe actuator is attached when the actuator is in a first position, andfor imparting a second and greater amount of friction on the at leastone pull cable when the actuator is moved away from the first position.According to this aspect of the present invention, the first positionmay correspond to a neutral position of the actuator wherein the tipassembly is aligned with the longitudinal axis of the shaft, or aneutral position of the actuator wherein the radius of curvature of thedistal end of the tip assembly is neither being actively reduced orincreased, and the second position may correspond to a position of theactuator that is other than the neutral or rest position.

As should be appreciated by those skilled in the art, it is desirablethat the actuators for changing the orientation of the tip assembly andfor controlling the radius of curvature of the distal end of the tipassembly remain in a fixed position, once actuated. Conventionally, thishas been achieved by providing a sufficient amount of friction betweenthe actuator and another surface on the handle 122 to resist movement ofthe actuator unless a certain amount of force is applied to theactuator. For example, in FIG. 22, by tightening shoulder nut 2224 thatholds the thumbwheel in position, a greater amount of force must beapplied to the thumbwheel to rotate the thumbwheel from one rotationalposition to another. Similarly, and with respect to the slide actuator124, by tightening the two screws 2260 that hold the slider grip 2252 inposition against an undersurface of the handle section, a greater amountof force must be applied to the slide actuator 124 to move the slideactuator 122 from one position to another.

Although this conventional approach is straightforward, it results inthe same amount of friction being applied to the actuator(s) in allpositions, and not merely those positions that deviate from a neutral orrest position. Thus, in use, it can be difficult to ascertain whetherthe orientation of the tip assembly or the radius of curvature of thedistal end of the tip assembly is in a neutral state, without visuallylooking at the handle. This can be problematic, as the user of thecatheter would need to divert his or her attention to visually inspectthe position of the actuator(s). Further, Applicants have determinedthat the frictional force imparted by the mechanisms that maintain thecables and actuators in a fixed position can significantly decrease overtime, for example, while stacked on the shelf, oftentimes requiring thatthe mechanisms used to impart such friction (e.g., the shoulder nut andthe screws) be tightened prior to use. It is believed that thisphenomena is due to material creep associated with the various materialsused to form the actuator mechanisms. This decrease in frictional forceis especially apparent where the catheter has been brought to elevatedtemperatures during a sterilization cycle, as the materials from whichthe handle and the control mechanisms are formed have a tendency toyield at elevated temperatures. Although the various mechanisms may betightened after sterilization, such tightening may contaminate thesterile nature of the catheter, and is undesirable in a clinicalsetting.

According to a further aspect of the present invention, each of thethumbwheel actuator and the slide actuator may include means forimparting a first amount of friction on at least one pull cable to whichthe actuator is attached when the actuator is in a first position, andfor imparting a second and greater amount of friction on the at leastone pull cable when the actuator is moved away from the first position.This difference in the frictional force can be perceived by the user toalert the user as to when the actuator is in a neutral or rest position,without visually inspecting the actuator. Further, because thefrictional forces on the actuating mechanisms are reduced in a neutralor rest position, the catheter may be sterilized with the actuator(s) ina neutral or rest position, thereby reducing yielding of the actuationmechanism during sterilization.

According to one embodiment that is directed to the thumbwheel actuator,the means for imparting different amounts of friction may include aplurality of detents formed in the planar rear surface of the handlehousing that cooperate with corresponding plurality of detents in alower surface of the thumbwheel. In this embodiment, each of theplurality of detents in the lower surface of the thumbwheel receives aball or bearing that sits partially within the respective detent. In afirst neutral position, each of the balls also rest within a respectivedetent in the rear surface of the handle and exert a first amount offriction on the thumbwheel and the pull cables attached thereto. But, asthe thumbwheel is rotated, the balls ride outside the detent in the rearsurface of the handle onto the elevated surface above, thereby exertinga second and greater amount of friction on the thumbwheel and the pullcables attached thereto. According to one embodiment, this second amountof friction is sufficient to prevent the thumbwheel from returning toits neutral position. FIGS. 22, 26, 27, and 28 illustrate oneimplementation of a means for imparting different amounts of frictionfor a thumbwheel actuator 122 according to this embodiment of thepresent invention.

As shown in FIGS. 22, 26, 27, and 28, the planar rear surface 2210 ofthe right section 2200R includes a plurality of detents 2212 formedtherein. A corresponding number of detents 2215 are provided in anundersurface of the thumbwheel 122 (FIGS. 26-28). Within each of theplurality of detents 2215 in the undersurface of the thumbwheel is aball or bearing 2214. The balls or bearing may be made from any suitablematerial, such as stainless steel, or may alternatively be made from ahard plastic. The balls or bearings 2214 may be fixed in position forexample, with an epoxy, or permitted to rotate within the detents 2215.It should be appreciated that the balls or bearings 2214 mayalternatively be seated within the detents 2212 in the planar rearsurface 2211 of the right section of the handle 2200R. In a neutral orrest position, for example, corresponding to an orientation of the tipassembly that is parallel to the longitudinal axis of the shaft, each ofthe plurality of balls rests within a corresponding detent 2212 in theplanar rear surface 2211. Such a resting or neutral state is depicted inFIG. 27 which is a schematic cross sectional view of the thumbwheel ofFIG. 22. As may be appreciated, this neutral or rest positioncorresponds to a position of reduced friction on the thumbwheel 122 inwhich the friction disk 2226 is compressed to only a small degree, andthus, to a reduced frictional force on the pull cables that are attachedto the thumbwheel.

As the thumbwheel 122 is rotated from this neutral or rest position, theballs 2214 ride up and out of their respective detents 2212 and alongthe path 2265 indicated in FIG. 22. In this second position wherein eachof the balls contacts the elevated planar rear surface 2211, a secondand greater amount of friction is imparted to the thumbwheel, and thus,the pull cables attached thereto, that tends to prevent the thumbwheelfrom moving to another position without further rotational force appliedto the thumbwheel. FIG. 28 is a schematic cross sectional view of thethumbwheel of FIG. 22 illustrating a state in which the thumbwheel is ina position other than the neutral or rest position. As can be seen inFIG. 28, each of the balls 2214 rests upon the elevated planar rearsurface 2211 and the friction disk 2226 is compressed relative to thatshown in FIG. 27. As shown best in FIG. 22, each of the detents 2212 inthe planar rear surface 2211 may include lead in/lead out sections 2267that are gradually tapered to the level of the planar rear surface 2211to facilitate smooth movement of the balls 2214 out of and into thedetents 2212.

Although the present invention is not limited to the number of detents2212, 2215 incorporated into the handle and the thumbwheel, Applicantshave found that three detents spaced equally about a circumference ofthe planar rear surface 2211 and the thumbwheel 122 distributes stressevenly about the thumbwheel 122 and permits a sufficient amount ofrotation before another detent 2212 is encountered. Furthermore,although the present invention is not limited to the amount of forceapplied to the thumbwheel to change the position of the thumbwheel,Applicants have empirically determined that a force of approximately 4to 8 pounds is sufficient to resist any forces on the pull cables.Moreover, this amount of force is sufficient so that the thumbwheelcannot be moved inadvertently, and does not require great strength bythe user. This amount of force also accounts for any yielding duringstorage and/or sterilization.

Although this embodiment of the present invention has been described interms of a plurality of detents in a surface of the handle and acorresponding number of detents that hold a ball or bearing in anundersurface of the thumbwheel, the present invention is not so limited.For example, and as discussed above, the detents in the planar surface2211 of the handle 120 may hold the balls or bearings 2214 and not thethumbwheel. Moreover, it should be appreciated that other means ofimparting different frictional forces on the thumbwheel may be readilyenvisioned. For example, rather than detents, the rear planar surface2211 may be contoured to include a plurality of ramps (for example,three ramps). The undersurface of the thumbwheel 122 may include acorresponding plurality of complementary shaped ramps such that when thethumbwheel 122 is in a neutral or rest position, a minimum of frictionis imparted, and as the thumbwheel 122 is rotated, the heightenedsurface of the ramps on the undersurface of the thumbwheel 122 contactsa heightened surface of the ramps in the planar surface. As thethumbwheel 122 is rotated further, addition friction is imparted.

According to another embodiment that is directed to the slide actuator,the means for imparting different amounts of friction may include a rampdisposed on or formed within the handle 120. In this embodiment, theapex of the ramp corresponds to a neutral position of the slide actuator122. In this neutral position, a minimum amount of friction is appliedto the slider 2232 and the pull cables 1110 a, 1110 b attached thereto.As the slider 2232 is moved forward or backward away from the neutralposition, the slider 2232 is pushed toward the thumbwheel and aninterior surface of the housing to impart a great amount of friction onthe slider and the pull cables attached thereto. As with the thumbwheel,this second amount of friction is sufficient to prevent the slider fromreturning to its neutral position.

FIGS. 23, 24, and 26 illustrate one implementation of a means forimparting different amounts of friction for a slide actuator 124. Asshown in these Figures, the undersurface of the left section 2200Lincludes a ramp 2610. The ramp may be integrally formed within the leftsection 2200L of the handle 120, or alternatively, the ramp 2610 may beseparate from the handle and attached thereto. As illustrated in FIG. 26which is a schematic cross sectional view of the slide actuator 124shown in FIGS. 1 and 22, the ramp 2610 includes a central section ofdecreased thickness and proximal and distal sections that increase inthickness away from the central section until flush with theundersurface of the left section. The top surface of the slider 2232that contacts the undersurface of the left section 2200L of the handlemay have a complementary shape to the ramp as shown in FIGS. 23 and 24.In the position shown in FIG. 23, the slide actuator is in a neutral orrest position corresponding to a first radius of curvature of the distalend of the tip assembly. The two screws 2260 force the slider grip 2252and the slider 2232 closer to one another and compress the preload pads2254 therebetween. In the neutral or rest position shown in FIGS. 23 and25, the preload pads 2254 are compressed to only a minimal extent.However, as the slider 2232 is moved away from the neutral or restingposition, the shape of the ramp 2610 (and the slider 2332) imparts anadditional frictional force that tends to separate the slider 2232 fromthe slider grip 2252, thereby compressing the preload pads 2254 to agreater extent, as illustrated in FIG. 24. This additional frictionalforce resists the slide actuator 124 from changing position, absentfurther force on the slide actuator 124.

Although this embodiment of the present invention has been described interms of a ramp formed within or disposed on an undersurface of thehandle 122, the present invention is not so limited. For example, theramp may alternatively be formed on an outer surface of the handle andprovide similar functionality. Other means for imparting differentfrictional forces on the slide actuator may be readily envisioned bythose skilled in the art.

Although the above described embodiments for imparting a varying amountof friction on at least one pull cable have been described with respectto a catheter in which the diameter of curvature of the distal end, orthe orientation of the distal end of the tip assembly, can be changed bymanipulation of an actuator attached to the pull cable, the presentinvention is not so limited. For example, the means for imparting avarying amount of friction may also be used with a push/pull cable and amovable electrode described above. Alternatively, the means forimparting a varying amount of friction may be used to impart varyingamounts of friction to a cable that is used to deploy a braidedconductive member in the manner described in co-pending and commonlyassigned U.S. patent application Ser. No. 09/845,022, entitled APPARATUSAND METHODS FOR MAPPING AND ABLATION IN ELECTROPHYSIOLOGY PROCEDURES,filed Apr. 27, 2001, and incorporated herein by reference. Accordingly,it should be appreciated that this embodiment of the present inventionmay be used to impart varying amounts of friction on any cable thatcontrols movement of one portion of the catheter with respect toanother.

FIG. 29A illustrates another handle that may be used with embodiments ofthe present invention. In the embodiment depicted in FIG. 29A, thehandle 120 includes three actuators 122, 124, and 124 a for controllingmovement of the tip assembly 140. For example, the thumbwheel actuator122 may be used to change the orientation of the tip assembly 140relative to the longitudinal axis of the shaft 110 of the catheter 100in one or two different directions depending on the number of cablesattached thereto. The first slide actuator 124 may be used to increaseand/or decrease the radius of curvature of the distal end 144 of the tipassembly 140. The second slide actuator 124 a may be used to control theorientation of the of the tip assembly 140 relative to the longitudinalaxis of the shaft 110 of the catheter 100 in one or two differentdirection of movement that are orthogonal to the directions provided byuse of the thumbwheel actuator 122. Alternatively, the second slideactuator 124A may be used to move a sliding electrode (See FIG. 18)proximally and distally along the distal end of the tip assembly.Alternatively still, the thumbwheel actuator 122 or the first slideactuator 124 may be used for changing the orientation of the tipassembly or the radius of curvature of the distal end in a firstdirection, and the second slide actuator 124 a may be used for changingthe orientation of the tip assembly or the radius of curvature in theopposite direction. Alternatively still, the first slide actuator 124may be used for controlling an active bend (see FIG. 21), the thumbwheelactuator 122 may be used for changing the radius of curvature of thedistal end of the tip assembly, and the second slide actuator 124 a maybe used for changing the orientation of the tip assembly in a firstand/or second direction (e.g., for steering of the proximal end of thetip assembly.) FIG. 29B illustrates another handle that includes a thirdactuator. In the embodiment illustrated in FIG. 29B, the third actuatoris a plunger-type actuator 126 that is conventionally used for a varietyof different purposes in the medical industry. In the illustratedembodiment, the plunger-type actuator may be used to move a slidingelectrode proximally and distally along the distal end of the tipassembly, with the thumbwheel 122 and slide 124 actuators being used forsteering of the proximal end of the tip assembly and changing the radiusof curvature of the distal end of the tip assembly, respectively, orvice versa. Although the use of a handle having up to three differentactuators has been described, it should be appreciated that more thanthree different actuators may be provided. For example, a thumbwheelactuator, two slide actuators, and a plunger-type actuator may be usedto control an active bend, a sliding electrode, changing the radius ofcurvature of the distal end, and steering of the proximal end of the tipassembly.

FIGS. 30-32 illustrate a control handle for a catheter according toanother embodiment of the present invention. As illustrated in FIG. 31,a surface of the handle 120 may include a plurality of ribs or detents3010 to provide tactile feedback to a user. For example, as the slidergrip 2252 is moved proximally and distally on the handle, this movementcan be felt by the user. Such feedback permits the user to understandthat the radius of curvature of the distal end of the tip assembly, orthe orientation of the tip assembly has been changed, without requiringthe user to visually perceive the movement of the slider grip 2252. Inthe embodiment illustrated in FIG. 31, the plurality of ribs are formedintegrally with the handle 120 and disposed on an outer surface thereof.To prevent the preload pads 2254 from catching on the ribs or detents3010, a hard thin layer of material such as plastic may be applied tothe surface of the preload pads that contact the outer surface of thehandle 120. In the embodiment shown, the leading and trailing edges ofthe pads 2254 are also curved away from the outer surface of the handle120 to avoid rough movement.

FIG. 32 illustrates an alternative embodiment of the handle 120 thatincludes a plurality of ribs or detents 3010 that are formed integrallywith the handle 120 and disposed on an inner surface of the handle 120.As the preload pads 2252 do not directly contact the ribs or detents3010, a hard layer such as that described above with respect to

FIG. 31 is not necessary. With each of the embodiments described above,it should be appreciated that the ribs or detents 3010 should be largeenough to provide tactile feedback to the user, but not so large as tobe disturbing to the user, or to result in rough and abrupt movement ofthe slide actuator 124 when moved from one position to another.Applicants have empirically determined that a protrusion of the ribs ordetents 3010 approximately 1 mm above, or below the surface of thehandle meets these objectives. Although the use of ribs or detents hasbeen described with respect to providing feedback to a user on movementof the distal end of the catheter, the present invention is not solimited. For example, the ribs or detents may be used to providefeedback relating to movement of a movable electrode, or a braidedconductive mesh.

Accordingly, the use of tactile features for providing feedback to auser may be used wherever it is useful to provide feedback to a user onthe movement of one portion of the catheter with respect to another.

According to another embodiment of the present invention, a handle foruse with a catheter having an elongated shaft and a tip assembly isprovided. According to this embodiment, the handle may include graphicalindicia indicative of a radius of curvature of a distal end of the tipassembly. This embodiment is now described with respect to FIG. 33.

As shown in FIG. 33, the handle 120 of the catheter 100 can includegraphical indicia 3310 that identifies the radius of curvature of thedistal end of the tip assembly.

In the embodiment shown, the graphical indicia 3310 are disposed on thehandle 120 adjacent to the slide actuator 124, which in this embodimentcontrols the radius of curvature of the distal end of the tip assembly.As illustrated, the graphical indicia 3310 identify the diameter ofcurvature in centimeters, with a position of two centimeterscorresponding to a neutral position of the slide actuator. Movement ofthe slide actuator 124 distally on the handle 120 increases the radiusof curvature of the distal end of the tip assembly, and movement of theslider 124 proximally on the handle 120 decreases the radius ofcurvature. Although not illustrated in FIG. 33, the graphical indicia3310 may also identify the number of circles formed by the distal end ofthe tip assembly. For example, a first numeric indicator can precedeeach of the illustrated numeric indicators to identify the number ofcircles formed by the distal end of the tip assembly. For example, anindicator of 2.1 can indicate two complete circles of the distal end ofthe tip assembly with a diameter of 1 cm, with an indicator of 1.2indicating one complete circle of the distal end of the tip assemblywith a diameter of 2 cm. Alternatively, the number of circles formed bythe distal end of the tip assembly may be placed on the other side ofthe slide actuator 124. Other representations of both the diameter ofcurvature and the number of circles formed by the distal end of the tipassembly may be readily envisioned. It should be appreciated that thegraphical indicia permit a user to roughly determine the diameter of anendocardial or epicardial site without recourse to otherinstrumentation, other than the catheter itself.

Although the provision of graphical indicia has been described withrespect to the slide actuator 124, it should be appreciated that asimilar provision may be made for the thumbwheel actuator 122. Ingeneral, although the provision of graphical indicia may associated withthe thumbwheel 122 may not be very useful when related to theorientation of the tip assembly, the operation of the thumbwheel 122 andthe slide actuator 124 may be reversed, such that the thumbwheel 122 isused to control the radius of curvature of the distal end of the tipassembly, and the slide actuator 124 is used to control the orientationof the tip assembly. Where the thumbwheel 122 is used to control theradius of curvature of the distal end of the tip assembly, graphicalindicia 3010 may be provided on the thumbwheel at different rotationalpositions (e.g., at zero degrees, at thirty degrees, as sixty degrees,etc. to serve a similar purpose.

Although the provision of graphical indicia has been described withrespect to providing feedback to a user on the radius of curvature ofthe distal end of the catheter, it should be appreciated that other usesmay be readily envisioned. For example, the use of graphical indicia maybe used to identify the state of deployment of a braided mesh that isdisposed at the distal end of the catheter, or to identify the locationof a movable electrode that is disposed on the distal end of thecatheter.

Temperature Sensing and Localization

Temperature sensing refers to a number of techniques whereby thetemperature in the vicinity surrounding distal end 144 of the tipassembly 140 may be measured. Measuring temperature is important,particularly during ablation procedures, so as to avoid overheating orcharring tissue. The catheter of the present invention can provide formeasuring the temperature of the distal end 144 of the tip assembly 140and the mapping electrodes disposed thereon at the same time. Thetemperature of the distal end 144 can then be used to provide feedbackfor control of ablation energy generator 170 and the temperature of themapping electrodes can be monitored to be certain that the tissue thatis being ablated is in fact being destroyed or rendered non-electricallyconductive.

In a further embodiment of the invention, one or more of the pluralityof ring or band-type electrodes 146 may be replaced with a ring orband-shaped temperature sensor. Reference is now made to FIG. 34, whichillustrates a ring-shaped ablation electrode 146 and a ring-shapedtemperature sensor 3410. Temperature sensor 3410 may be a thermocouple,thermistor, or any other device for sensing temperature. The temperaturesensor 3410 detects the heat of the tissue during ablation by ring orband-shaped ablation electrode 146. Temperature sensing is importantduring ablation because overheated tissue may explode or char, releasingdebris into the bloodstream. Ablation electrode 146 is connected toconnector 130 (FIG. 1) via wire 3420, which in turn connects to ablationenergy generator 170; ring-shaped temperature sensor 3410 is connectedto connector 130 via wire 3430, which in turn connects to controller150. Ring-shaped electrode 146 can serve as both a reference electrodeand an ablation electrode, and may be switched between applications bythe controller 150 or by a human operator.

A temperature sensor or sensors, such as, but not limited to one or morethermocouples may be attached to the catheter 100 for temperaturesensing during ablation procedures. The temperature sensor may be incontact with the heart tissue or, alternately, may not be in contactwith the heart tissue. In other embodiments, temperature sensors may bedisposed within one or more of the mapping electrodes 146, 147, forexample in a hole drilled within the electrode. One skilled in the artwill appreciate that more than one temperature sensor may be used in anyparticular configuration of catheter 100.

Localization refers to a number of techniques whereby the location ofcatheter 100 in a patient can be determined. Apparatus and methods forlocalization can be incorporated into catheter 100.

Referring again to FIG. 34, the distal end 144 of the tip assembly 140may include an electromagnetic sensor 3450 that may be used forlocalization. Electromagnetic sensor 3450, may be fixed within the tipassembly 140 of the catheter 100 using any suitable mechanism, such asglue or solder. The electromagnetic sensor 3450 generates signalsindicative of the location of the electromagnetic sensor. A wire 3440electrically connects the electromagnetic sensor 3450 to the controller150, allowing the generated signals to be transmitted to the controller150 for processing.

In addition to the electromagnetic sensor 3450 fixed in the distal endof the tip assembly 140, a second electromagnetic sensor (not shown) maybe provided that is fixed relative to the patient. The secondelectromagnetic sensor is attached, for example, to the patient's body,and serves as a reference sensor. A magnetic field is also provided,which is exposed to the electromagnetic sensors. Coils within eachelectromagnetic sensor generate electrical currents when exposed to themagnetic field. The electrical current generated by the coils of eachsensor corresponds to a position of each sensor within the magneticfield. Signals generated by the reference electromagnetic sensor andelectromagnetic sensor 3450 fixed to the catheter are analyzed by thecontroller 150 to ascertain a precise location of electromagnetic sensor3450.

Further, the signals can be used to generate a contour map of the heart.The map may be generated by contacting the distal end 144 of the tipassembly 140 with the heart tissue at a number of locations along theheart wall. At each location, the electric signals generated by theelectromagnetic sensors are transmitted to the controller 150, or toanother processor, to determine and record a location of the distal endof the tip assembly. The contour map is generated by compiling thelocation information for each point of contact. This map may becorrelated with heart signal data, measured by one or more electrodes onthe distal end of the tip assembly, for each location to generate a mapof both the shape and electrical activity of the heart. Signalsgenerated by the electromagnetic sensors may also be analyzed todetermine a displacement of the distal end of the tip assembly caused byheartbeat.

As an alternative to the use of electromagnetic sensors otherconventional techniques, such as ultrasound or magnetic resonanceimaging (MRI) can also be used for localization of tip assembly.Moreover, an impedance-based sensor can also be incorporated into thetip assembly. In an impedance-based system, several, such as three, highfrequency signals are generated along different axes. The catheterelectrodes may be used to sense these frequencies, and with appropriatefiltering, the strength of the signal and thus the position of thecatheter can be determined.

One skilled in the art will appreciate that the construction of catheter100 may be optimized to make use of the various localization techniques.

Methods for Making the Tip Assembly

FIGS. 5-10 illustrate a number of different jigs that may be used toform a tip assembly having a fixed bend of approximately ninety degreesfollowed by an arcuately curved distal end. Each of these jigs may beused with a finished catheter (i.e., a catheter which is already fullyassembled, and including a handle 120 and electrodes 146, 147 disposedon the distal end of the tip assembly 140), a partially finished tipassembly (i.e., a tip assembly 140 that includes electrodes 146, 147,that is not yet attached to shaft 110 and the handle 120 (FIG. 1)), oran unfinished tip assembly 140 (i.e., a tip assembly 140 without anyelectrodes 146, 147).

FIGS. 5 and 6 illustrate a first jig 500 that is formed from a hollowtube. In one embodiment, the hollow tube is formed from hypodermicstainless steel tubing, although other materials, such as a hightemperature plastics such as TEFLON, DELRIN, etc., may alternatively beused. The material from which the jig 500 is formed should be thermallystable, such that its shape does not change when subjected totemperature in the range of 200-400 degrees Fahrenheit. In oneembodiment, the tube used to form the jig 500 has an outer diameter ofapproximately 0.83 inches and an inner diameter of approximately 0.72inches to accommodate a tip assembly 140 that is approximately 6 Frenchin diameter, although these dimensions may be varied to accommodatedifferent diameter tip assemblies. For example, to accommodate a tipassembly that is 10 French in diameter, a larger diameter tube would beused. As shown in FIG. 5, the distal end of the jig 500 is formed in acircle having an inner diameter of approximately 0.44 inches and anouter diameter of approximately 0.61 inches. Although the presentinvention is not limited to any particular dimensions, these dimensionsmay be used to form a tip assembly 140 in which the diameter ofcurvature of the distal end 144 in a resting state is approximately 20mm. Further, and as described in more detail below, these dimensions areselected to account for a certain amount of rebounding (approximatelyfifteen to twenty percent) in the tip assembly 140 after removal fromthe jig. Although embodiments of the present invention are not limitedto a tip assembly having a diameter of curvature of approximately 20 mmin a resting state, this size advantageously permits the catheter to beused for mapping and/or ablation procedures within a blood vessel, suchas a pulmonary vein. It should be appreciated that for other endocardialor epicardial sites, other dimensions may be used.

As shown in FIG. 6, the jig 500 has a first straight region 510,followed by a curved region 520 having an approximately ninety degreebend relative to the straight region 510, and terminates in an arcuatelyshaped curved region 530 defining approximately a circle (i.e., spanningapproximately 360 degrees). In one embodiment, the straight region 510is approximately 0.125 inches in length, and the curved region 520 hasan inner radius 515 of approximately 0.2 inches. It should beappreciated that other dimensions may be used to impart a differentshape to the tip assembly, and to accommodate tip assemblies having adifferent outer diameters (e.g., a 10 French diameter tip assembly).

According to one embodiment of the present invention, the tip assembly140 is inserted into the straight region 510 of the jig 500 and thedistal end 144 of the tip assembly 140 is advanced until the very distalend of the tip assembly 140 is adjacent the distal end of the jig 500.The jig 500 and the tip assembly 140 are then heated at a predeterminedtemperature for a predetermined time to permanently shape the tipassembly 140. Applicants have found that heating the jig 500 and the tipassembly 140 at a temperature of approximately 200 to 400 degreesFahrenheit for approximately thirty minutes to an hour is sufficient topermanently shape the tip assembly 140 to the desired shape. It shouldbe appreciated that the lower the temperature, the greater amount oftime is needed to permanently shape the tip assembly 140, and that thetime and temperature to which the tip assembly 140 and the jig 500 areheated may vary dependent upon the materials used to form the tipassembly 140 and the jig 500. It should further be appreciated thatbecause catheters may be sterilized prior to use or after use, thetemperature to which the tip assembly 140 and the jig 500 is heatedshould be approximately 20 degrees Fahrenheit above the temperature atwhich the catheter is sterilized. This helps to prevent the tip assembly140 from returning to its original shape during sterilization. Duringsterilization, a retainer may be used to hold the tip assembly 140 inthe desired shape.

After heating the tip assembly 140 and the jig 500 for the predeterminedtime at the predetermined temperature, the tip assembly 140 and the jig500 are allowed to cool, and the tip assembly 140 is removed from thejig 500. After removal, Applicants have found the arcuately curveddistal end 144 of the tip assembly 140 tends to rebound by approximatelyfifteen to twenty percent, but that further rebounding at temperaturessimilar to those of human body temperature does not occur. Further, bymodifying the materials from which the tip assembly 140 is formed, andby controlling the temperature and the time at which the tip assembly140 is shaped, rebounding to less than three percent is expected. Itshould be appreciated that because a certain amount of rebounding is tobe expected, the dimensions of the jig 500 should be sized toaccommodate the expected amount of rebounding.

The jig of FIGS. 5 and 6 may be used to impart a desired shape to thetip assembly 140 of a finished catheter or to a partially finished tipassembly. For example, in the described embodiment, the length of thestraight region 510 is relatively short to permit the tip assembly 140of a finished catheter to be inserted into the jig 500 without damagingthe electrodes 146, 147. This can be advantageous in a manufacturingsetting, as finished catheters can be shaped as desired afterconstruction and testing, and prior to shipment to an end user. This mayallow fewer distinct catheters to be stocked by the manufacturer of thecatheter. Alternatively, in a hospital setting, the ability to shape afinished catheter can allow fewer catheters to be stocked at thehospital, with each of the catheters being capable of being shaped asdesired, prior to use.

For use with partially finished tip assemblies, the length of thestraight region 510 may be lengthened, with any excess material beingcut to length as desired. Moreover, with partially finished tipassemblies, the distal end of the jig 500 may form more than onecomplete circle, or may form a helical shape. Although the jig 500depicted in FIGS. 5 and 6 was used to receive a tip assembly, it shouldbe appreciated that a solid wire of a similar shape may alternatively beused. For example, the hollow stock from which the tip assembly isformed may be fed onto a solid wire having the desired shape, and thenheated at an elevated temperature to produce the desired shape. Theformed stock can then be removed from the wire, cut to the desiredlength, and finished in a conventional manner.

FIGS. 7 and 8 illustrate a second jig that may also be used to form atip assembly having the desired shape. In particular, the jig of FIGS. 7and 8 may be used to permanently shape the distal end of a catheter sothat it includes an approximately ninety degree bend followed by anarcuately curved section. According to this embodiment, the jig 700includes a cylindrical mandrel 740 and a cylindrical retainer 750. Thecylindrical mandrel 740 and the cylindrical retainer 750 may be formedfrom any suitable high temperature materials, such as stainless steel,aluminum, anodized aluminum, or high temperature plastics. In oneembodiment, the mandrel 740 has an outer diameter of approximately 0.75inches and is approximately 2.5 inches long, and the retainer 750 has aninner diameter that is slightly greater than the outer diameter of themandrel 740, so that the mandrel 740 can be fit within. Although thepresent invention is not limited to these dimensions, theabove-identified dimensions may be used to shape the distal end tipassembly of a catheter so that it is uniquely suited for use inside ablood vessel; such as a pulmonary vein, and to accommodate ananticipated amount of rebounding after removal of the distal end tipassembly from the jig. It should be appreciated that for applicationsrelating to other endocardial sites, other dimensions may be suitablyemployed.

As shown in FIGS. 7 and 8, the mandrel 740 has a passageway to receive atip assembly 140 that includes a first straight region 710, a curvedregion 720 having an approximately ninety degree bend relative to thestraight region 710, and an arcuately shaped curved region 730 defininga circle. The passageway may be formed in a conventional manner, forexample with a milling machine. In one embodiment, the straight region710 is approximately 1.9 inches in length, and the curved region 720 hasan inner radius 715 of approximately 0.2 inches; the depth of thepassageway is approximately 0.068 inches and the width is approximatelythe same. The described dimensions are selected to shape a tip assemblythat is well suited for use within a blood vessel such as a pulmonaryvein, although it should be appreciated that other dimensions may besuitably employed for use with different anatomical structures and fordifferent applications. Again, the dimensions of the mandrel 740 and theretainer 750 should be selected to accommodate the expected amount ofrebounding. In the embodiment shown, the arcuately shaped curved region730 is spaced apart from the end of the mandrel 740 to facilitateinsertion of the mandrel 740 into the retainer 750.

According to one embodiment of the present invention, a tip assembly 140is placed into the passageway, and the mandrel 740 and the tip assembly140 are inserted into the retainer 750. The retainer 750 acts to holdthe tip assembly 140 in place within the passageway of the mandrel 740.The jig 700 and the tip assembly 140 are then heated at a predeterminedtemperature for a predetermined time to permanently shape the tipassembly 140 in a manner similar to that described above with respect tothe first jig 500. Because of the larger thermal mass of the jig 700relative to the jig 500, Applicants have found that a longer time may beneeded to shape the tip assembly 140 than with the first jig 500, forexample, about 20 additional minutes. To lessen the amount of timerequired to shape the tip assembly 140, the mandrel 740 may be hollowedout, for example. After heating the tip assembly 140 and the jig 700 forthe predetermined time at the predetermined temperature, the tipassembly 140 and the jig 700 are allowed to cool, and then the tipassembly 140 is removed from the jig 700. As with the jig of FIGS. 5 and6, the jig 700 may be used to impart a desired shape to the tip assembly140 of a finished catheter or to a partially finished tip assembly.Indeed, because the tip assembly 140 is placed within the passagewayrather than being threaded through it, the jig 700 is particularly wellsuited for use with a finished tip assembly, as damage to the finishedtip assembly resulting from contact with the jig can be avoided.

FIGS. 9 and 10 illustrate another jig that may be used to form a tipassembly 140 having an approximately ninety degree bend followed by anarcuately curved distal end. According to this embodiment, the jig 900includes a disk-shaped mandrel 940 and a circular cover 950. Thedisk-shaped mandrel 940 and the circular cover 950 may again be formedfrom any suitable high temperature materials, such as stainless steel,aluminum, anodized aluminum, or high temperature plastics. The cover 950is removably attached to the mandrel 940 by a fastener 960, such as athreaded screw, that is passed through an aperture 980 in the cover 950.The mandrel 940 may include a threaded aperture to receive the fastener960. Attached to the mandrel 940 is a tubular extension 970 that may bemade from any suitable material, and which is attached, for example,with a high temperature epoxy or by welding to the mandrel. The tubularextension 970 may be used to support the proximal end 142 of the tipassembly 140 without substantially increasing the thermal mass of thejig 900.

As shown in FIGS. 9 and 10, the mandrel 940 has a passageway to receivea tip assembly 140 that includes a first straight region 910, a curvedregion 920 having an approximately ninety degree bend relative to thestraight region 910, and an arcuately shaped curved region 930 defininga circle. The arcuately shaped curved region 930 may be formed bymilling an annular groove in a top surface of the mandrel 940, while thestraight region 910 may be formed by drilling a through hole through asection of arcuately shaped curved region 930, for example. A ninetydegree bend is formed at the intersection of the annular groove and thethrough hole. In one embodiment, the arcuately shaped curved region 930has an outer diameter of approximately 0.5 inches and the annular groovehas a width of approximately 0.07 inches. The above-described dimensionsare selected to shape the tip assembly so that it is well suited for usewithin a blood vessel such as a pulmonary vein, although it should beappreciated that other dimensions may be suitably employed for use withdifferent anatomical structures and for different applications. Thedepth of the groove should be sufficiently greater than the outerdiameter of the tip assembly 140 so that the bend in the tip assembly140 takes place over a length of the tip assembly 140. For example, inone embodiment, the depth of the groove is approximately twice the widthof the groove to avoid an immediate ninety degree bend in the tipassembly 140. Such an immediate bend could interfere with operation ofthe control cables that are used to adjust the radius of curvature ofthe distal end 144 of the tip assembly 140. Again, the dimensions of themandrel 940 should be selected to accommodate the expected amount ofrebounding, and the desired dimensions and shape of the tip assembly140.

According to one embodiment of the present invention, a tip assembly 140is threaded through the tubular extension 970 and the straight region910 of the mandrel 940, and the distal end 144 of the tip assembly 140is placed into the annular groove in the mandrel 940. The cover 950 isthen fastened to the mandrel 940. The cover 950 acts to hold the tipassembly 140 in place within the passageway of the mandrel 940. The jig900 and the tip assembly 140 are then heated at a predeterminedtemperature for a predetermined time to permanently shape the tipassembly 140 in a manner similar to that described above with respect tothe first and second jigs. After heating the tip assembly 140 and thejig 900 for the predetermined time at the predetermined temperature, thetip assembly 140 and the jig 900 are allowed to cool, and then the tipassembly 140 is removed from the jig 900.

As with the previously described jigs 500 and 700, the jig 900 may beused to impart a desired shape to the tip assembly 140 of a finishedcatheter or to a partially finished tip assembly. Because the distal endof the tip assembly is inserted straight ahead into the mandrel 940,rather than along a curved path, the jig 900 is also particularly wellsuited for use with a finished tip assembly, as damage to the finishedtip assembly resulting from contact with the jig can be avoided.

Although the jigs 500, 700, and 900 of FIGS. 5-10 have been illustratedand described as being useful in forming a tip assembly having a fixedbend of approximately ninety degrees followed by an arcuately curveddistal end, it should be appreciated that each of these jigs may also beused or modified for use with a tip assembly including an active bend,such as described above with respect to FIG. 19. For example, forcreating a permanent bias of a few degrees relative to the straightregions 510, 710, and 910, the approximately ninety degree bend may havea larger radius that may be varied according to the intended use of thetip assembly. As noted above with respect to FIG. 19, by permanentlybiasing the intermediate section 2180 (FIG. 19) away from the straightregions 510, 710, and 910, bending takes place in a known and controlledmanner. Moreover, it should be appreciated that rather than terminatingin a curved region 530, 730, 930 that spans approximately 360 degrees ina single plane (e.g., a circle), the curved region 530, 730, and 930 maybe formed in a helical shape.

Methods of Use

As discussed above, the catheter system of the invention may be used inmapping and/or ablation applications. In one embodiment of theinvention, the mapping or ablation is performed in the heart of apatient. In the mapping application, multiple signals may be receivedfrom the heart tissue via multiple electrodes on the catheter. Eachelectrode may measure a continuous signal (i.e., electrogram) from theheart tissue. The continuous signal may represent the voltage of theheart tissue in contact with the electrode, with respect to a referencevoltage, as it changes with time. The reference voltage may be obtainedusing a dedicated reference electrode or another measurement electrode.The quality of the signal received by each electrode improves as boththe size of the electrode and the isolation of the electrode increases.

Preferably, multiple electrodes are employed, such that multipleelectrograms may be obtained simultaneously. This allows for multipledata points, which can result in a more precise mapping of the heartsignal and a shorter required measurement time. A shorter measurementtime advantageously reduces the x-ray exposure to patients andphysicians during fluoroscopy, when employed during the catheterprocedure.

The mapping function of the catheter can be used for a number ofdifferent applications. For example, in one application, the cathetermay be used to measure the conductivity at various points of the septalwall, which separates the left and right sides of the heart, todetermine a preferred sight for puncture of the septal wall. In anotherapplication, the conductivity of the heart tissue may be measuredbetween adjacent electrodes in contact with the heart tissue todetermine the continuity of a lesion formed by ablation. In stillanother application, the catheter may used to identify electricalsignals within the heart that are characteristic of a number of heartconditions. For example, the focus site of an arrhythmia (e.g., atrialfibrillation, AV nodal tachycardia or tachycardia resulting fromWolff-Parkinson-White syndrome).

Reference is now made to FIG. 35, which illustrates a method ofinsertion of the catheter 100 into a patient 3510 in accordance with anembodiment of the present invention. The catheter 100 is inserted intothe patient via a blood vessel, e.g., subclavian vein, jugular vein, orfemoral vein. In FIG. 35, the catheter 100 is shown entering a femoralvein 3520 via an incision 3530 in the thigh of the patient 3510. Thecatheter 100 may be introduced into the vein using a sheath/dilator (notshown). The sheath/dilator may be anchored at the incision site, forexample by stitching the sheath/dilator to the patient's skin at thearea of incision 3530. From the incision site 3530 in the femoral vein3520, the catheter 100 may be advanced independently, or through asheath/dilator, up the inferior vena cava 3540 into the right atrium ofthe heart.

Reference is now made to FIG. 36, which illustrates a diagram of across-sectional view of the heart taken along line A-A in FIG. 35. Thecatheter 100 is shown entering the right atrium 3610 via the inferiorvena cava 3540. For passage of the catheter 100 into the left atrium,3620 the distal end of the catheter 100 may be passed trans-septallythrough the septal wall 3630. In one method, a puncture 3640 in theseptal wall 3630 is made at the foramen ovale, an area of the septalwall having a decreased thickness and decreased conductivity relative toother areas of the septal wall. As described previously, electrodes onthe distal end of the catheter 100 may be used to locate the foramenovale, or another preferred site to puncture the septal wall 3630. Asshown in FIG. 36, the distal end of the tip assembly 140 of the catheter100 traverses the septal wall 3630 from the right atrium 3610 and entersthe left atrium 3620. The distal end of the catheter 100 may be used formapping and/or ablation procedures in the left atrium 3620 or may bemaneuvered into the pulmonary vein(s) for mapping and/or ablation. Itshould be appreciated that the catheter may also be used to performmapping and/or ablation in the right heart, in the ventricles, or in anyother area of the heart or blood vessels of the circulatory system, andthat the catheter 1 need not pass through the septal wall to enter theseareas.

Referring now to FIG. 37, which is an expanded view of FIG. 36, in oneembodiment of the present invention, once inside the left atrium 3620,the distal end of the catheter 100 may be advanced towards the ostium ofone of the pulmonary veins 3710. In this embodiment, the radius ofcurvature of the distal end 144 of the tip assembly 140 is remotelyadjusted to snugly fit against the annular walls of the pulmonary vein3710 by manipulation of the actuator 122, 124 (FIG. 1) that controls theradius of curvature of the distal end 144 of the tip assembly 140. Inthis position, the graphical indicia 3310 (FIG. 33) on the handle 120may be used to give the user an indication of the diameter of the ostiumof the pulmonary vein at this location. Mapping may be performed, as canablation.

Because of the approximately ninety degree bend in the tip assembly 140,pressure applied to the handle 120 is translated via the shaft to forcethe arcuately curved distal end 144 of the tip assembly 140 tightlyagainst the ostium of the pulmonary vein 3710. In this position, theuser may also apply pressure to the actuator (e.g., the slide actuator124) that controls the radius of curvature of the distal end 144 of thetip assembly 140 to also apply an outwardly radial pressure that furtherforces the distal end 144 of the tip assembly 140 tight against theostium of the pulmonary vein 3710. Mapping may then be performed tolocate a focal trigger or triggers of atrial fibrillation. It should beappreciated that the ability to force the distal end 144 of the tipassembly 140 tightly against the inner circumferential surface of ablood vessel, such as the ostium of a pulmonary vein, enhances theability to accurately locate a focal trigger or triggers of atrialfibrillation.

Should ablation be determined to be an effective solution, ablationenergy may then be provided by the ablation energy generator 170(FIG. 1) to create a circular lesion around the circumference of theostium of the pulmonary vein 3710. By controlling which electrodes(disposed on the distal end of the tip assembly, but not shown) are usedto provide such ablation energy, a full circumferential lesion or apartial circumferential lesion may be created. Further, by monitoring ofthe temperature of at the site (for example, by using one or moretemperature sensors disposed along the distal end 144 of the tipassembly 140), care may be exercised to ensure that charring isprevented and that the appropriate temperatures necessary for ablationare achieved. After ablation, the mapping electrodes may then be used toverify that the electrical conductivity of the tissue has beendestroyed.

One advantage of using a catheter according to the invention in thedescribed method is that only a single catheter is necessary to (1)determine the location of the foramen ovale for passage through theseptal wall, (2) perform any desired mapping procedures, and (3) performany desired ablation procedures. This avoids the need for changingcatheters during procedures as between, for example, mapping andablation procedures. It may also reduce the number of removal andreinsertion operations needed during a patient's electrophysiology studyand treatment procedure. Further, because the radius of curvature of thedistal end of the tip assembly may be remotely altered within theendocardial site, the catheter may be used on any sized patient from aninfant or small animal to an adult or large animal, as “one size fitsall.” Moreover, should the size of a blood vessel or other anatomicalstructure be different than that which was anticipated, it is notnecessary to remove the catheter and insert another more appropriatelysized catheter. As noted above, this ability to be used with any sizedpatient can also reduce the need for a manufacturer or a care providerto stock a number of differently sized catheters.

The various configurations of the catheter illustrated in the figuresare exemplary. One skilled in the art will appreciate that the number,size, orientation, and configuration of the mapping electrodes and theablation electrodes, as well as various diameters and lengths of thecatheter can be provided depending upon the particular application.

Having thus described at least one illustrative embodiment of theinvention, various alterations, modifications, and improvements willreadily occur to those skilled in the art. Such alterations,modifications, and improvements are intended to be within the spirit andscope of the invention. Accordingly, the foregoing description is by wayof example only and is not intended as limiting. The invention islimited only as defined in the following claims and the equivalentsthereto.

1. A method of using a catheter having a handle, a flexible shaft havinga longitudinal axis, and a tip assembly, the shaft being connectedbetween the handle and the tip assembly, a proximal end of the tipassembly including a bend of approximately ninety degrees relative tothe longitudinal axis of the shaft, and the distal end of the tipassembly including an arcuate curve having a diameter, the arcuate curvebeing oriented in a plane that is approximately perpendicular to thelongitudinal axis of the shaft, the method comprising acts of:introducing the distal end of the tip assembly inside a heart of apatient; steering the tip assembly in a plane perpendicular to thelongitudinal axis of the shaft by actuating at least one pull cableanchored proximal to the tip assembly; contacting an inner surface ofthe heart vessel with the arcuate curve; and remotely, from outside thepatient, applying a radially outward pressure with the distal end of thetip assembly against the inner surface of the heart vessel.
 2. Themethod of claim 1, further comprising an act of: remotely decreasing thediameter of the arcuate curve to fit the distal end of the tip assemblyinto the heart vessel prior to the act of remotely applying the radiallyoutward pressure.
 3. The method of claim 1, wherein the distal end ofthe tip assembly includes at least one mapping electrode, the methodfurther comprising an act of: mapping electrical conductivity of theheart vessel using the at least one mapping electrode.
 4. The method ofclaim 1, wherein the distal end of the tip assembly includes at leastone ablation electrode, the method further comprising an act of:ablating tissue of the heart vessel using the at least one ablationelectrode.
 5. The method of claim 1, wherein the act of steeringcomprises aligning the arcuate curve with the heart vessel.
 6. Themethod of claim 1, wherein the arcuate curve approximately defines acircle.
 7. The method of claim 1, wherein the arcuate curve spansapproximately 360 degrees.
 8. The method of claim 1, further comprisingan act of: contracting the arcuate curve from a first configuration inwhich the arcuate curve spans approximately 360° or less to a secondconfiguration in which the arcuate curve spans more than 360°.
 9. Themethod of claim 1, further comprising an act of: contracting the arcuatecurve from a first configuration in which the arcuate curve spansapproximately 360° or less to a second configuration in which thearcuate curve spans at least 720°.
 10. The method of claim 1, whereinthe arcuate curve is adjustable from a diameter of approximately 5 mm toa diameter of approximately 50 mm.
 11. A method of using a catheterhaving a handle, a flexible shaft having a longitudinal axis, and a tipassembly, the shaft being connected between the handle and the tipassembly, a proximal end of the tip assembly including a bend ofapproximately ninety degrees relative to the longitudinal axis of theshaft, and the distal end of the tip assembly including an arcuate curvehaving a diameter, the arcuate curve being oriented in a plane that isapproximately perpendicular to the longitudinal axis of the shaft, themethod comprising acts of: introducing the distal end of the tipassembly inside a heart of a patient; contracting the arcuate curve froma first configuration in which the arcuate curve spans approximately360° or less to a second configuration in which the arcuate curve spansat least 720°; contacting an inner surface of a heart vessel with thearcuate curve in the second configuration; and remotely, from outsidethe patient, applying a radially outward pressure with the distal end ofthe tip assembly against the inner surface of the heart vessel.
 12. Themethod of claim 11, further comprising an act of: indicating, on thehandle, a number of circles formed by the distal end of the tipassembly.
 13. The method of claim 11, further comprising an act of:indicating, on the handle, a degree of contraction of the arcuate curve.14. The method of claim 11, wherein the arcuate curve is adjustable froma diameter of approximately 5 mm to a diameter of approximately 50 mm.